Multiple chemically functional oligomer blends

ABSTRACT

Thermomechanical and thermo-oxidative stabilities in resin composites across the range of aerospace &#34;engineering thermoplastic&#34; resins are improved by forming four crosslinks at each addition polymerization site in the backbone of the resin using crosslinking functionalities of the general formula: ##STR1## in the oligomers, wherein ##STR2## β=the residue an organic radical selected from the group consisting of: ##STR3## R 8  =a divalent organic radical; X=halogen; 
     Me=methyl 
     T=allyl or methallyl, 
     G=--CH 2  --, --S--, --CO--, --SO--, --O--, --CHR 3  --, or --C(R 3 ) 2  --; 
     i=1 or 2; 
     R 3  =hydrogen, lower alkyl, lower alkoxy, aryl, or aryloxy; and 
     Θ=--C.tbd.N, --O--C.tbd.N, --S--C.tbd.N, or --CR 3  ═C(R 3 ) 2 .

REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application based upon U.S.patent application Ser. No. 08/464,168, filed Jun. 5, 1995 now U.S. Pat.No. 5,714,566, which was a divisional application based upon U.S. patentapplication Ser. No. 08/327,942, filed Oct. 21, 1994, now abandoned.Application Ser. No. 08/327,942 is separately a continuation-in-partapplication based upon each of these seventeen, U.S. patentapplications:

    ______________________________________                                        APPLICATION                                                                             TITLE           FILING DATE                                         ______________________________________                                        06/773,381                                                                              Conductive, Thermally                                                                         September 5, 1985,                                            Stable Oligomers                                                                              pending                                             07/137,493                                                                              Polyester Oligomers and                                                                       December 23, 1987,                                            Blends          U.S. Pat. No. 5,705,598                             07/167,656                                                                              Multidimensional Ether                                                                        March 14, 1988                                                and Ester Oligomers                                                                           pending                                             07/168,289                                                                              Liquid Molding  March 15, 1988,                                               Compounds       U.S. Pat. No. 5,693,741                             07/176,518                                                                              Method for Making Multi-                                                                      April 1, 1988,                                                dimensional Polyesters                                                                        pending                                             07/212,404                                                                              Conductive, Multi-                                                                            June 27, 1988,                                                dimensional Oligomers                                                                         pending                                                       and Blends                                                          07/241,997                                                                              Polysulfoneimides                                                                             September 6, 1988,                                                            U.S. Pat. No. 5,530,089                             07/460,396                                                                              Polyethersulfone                                                                              January 3, 1990,                                              Oligomers and Blends                                                                          U.S. Pat. No. 5,446,120                             07/619,677                                                                              Advanced Composite                                                                            November 29, 1990,                                            Blends          U.S. Pat. No. 5,645,925                             07/639,051                                                                              Reactive Polyarylene                                                                          January 9, 1991,                                              Sulfide Oligomers                                                                             pending                                             08/043,824                                                                              Extended Acid Halide                                                                          April 6, 1993,                                                Capping Monomer U.S. Pat. No. 5,367,083                             08/079,999                                                                              Composites Containing                                                                         June 21, 1993,                                                Amideimide Sized Fibers                                                                       U.S. Pat. No. 5,403,666                             08/159,823                                                                              Polyimide Oligomers and                                                                       November 30, 1993,                                            Blends and Method                                                                             U.S. Pat. No. 5,455,115                                       of Curing                                                           08/161,164                                                                              Multidimensional                                                                              December 3, 1993,                                             Polyesters      pending                                             08/232,682                                                                              Multidimensional                                                                              April 25, 1994,                                               Polyamide Oligomers                                                                           U.S. Pat. No. 5,516,876                                       from Polyamine or                                                             Polyanhydride Hubs                                                  08/269,297                                                                              Ester or Ether Oligomers                                                                      June 30, 1994,                                                with Multidimensional                                                                         U.S. Pat. No. 5,550,204                                       Morphology                                                          08/280,866                                                                              Extended Amideimide                                                                           July 26, 1994,                                                Hub for Multidimensional                                                                      U.S. Pat. No. 5,512,676                                       Oligomers                                                           ______________________________________                                    

We incorporate these patent applications by reference.

TECHNICAL FIELD

The present invention relates to linear and multidimensional oligomersthat include multiple chemically functional crosslinking end cap(terminal) groups, and, preferably, to oligomers that have fourcrosslinking functionalities at each end of its linear backbone or eachmultidimensional arm. We call these products "multifunctionaloligomers." Composites made from these oligomers generally have improvedtoughness, thermomechanical stability, and thermo-oxidative stabilitybecause of the higher number of crosslinks that form upon curing. Theyconstitute engineering thermoplastics. Blends are prepared from mixturesof the oligomers and compatible polymers, oligomers, or both.

The present invention also relates to methods for making themultifunctional oligomers by condensing novel end cap reactive monomerswith appropriate reactive monomers for the chains of the respectivechemical backbones, and to the multiple chemically functional end capmonomers themselves.

BACKGROUND ART

The thermosetting resins that are commonly used today infiber-reinforced composites cannot be reshaped after thermoforming.Because errors in forming cannot be corrected, these thermosettingresins are undesirable in many applications. In addition, thesethermosetting resins, made from relatively low molecular weightmonomers, are relatively low molecular weight, and often form brittlecomposites that have relatively low thermal stabilities.

Although thermoplastic resins are well known, practical aerospaceapplication of high performance, fiber-reinforced thermoplastic resinsis relatively new. Fiber in such composites toughens and stiffens thethermoplastic resin. While the industry is exploring lower temperaturethermoplastic systems, like fiber-reinforced polyolefins or PEEKs, ourfocus is on high performance thermoplastics suitable, for example, forprimary structure in advanced high speed aircraft including the HighSpeed Civil Transport (HSCT). These materials should have high tensilestrength, and high glass transitions. Such materials are classified as"engineering thermoplastics." At moderate or high temperatures, the lowperformance, fiber-reinforced thermoplastic composites (polyolefins orPEEKS, for example) lose their ability to carry loads because the resinsoftens. Thus, improved thermal stability is needed for advancedcomposites to find applications in many aerospace situations. Theoligomers of the present invention produce advanced composites.

Advanced composites should be thermoplastic, solvent resistant, tough,impact resistant, easy to process, and strong. Oligomers and compositesthat have high thermomechanical stability and thermo-oxidative stabilityare particularly desirable.

While epoxy-based composites like those described in U.S. Pat. No.5,254,605 are suitable for many applications, their brittle nature andsusceptibility to degradation often force significant design concessionswhen these epoxies are selected for aerospace applications. The epoxiesare inadequate for applications which require thermally stable, toughcomposites, especially when the composites are expected to survive for along time in a hot, oxidizing environment. Recent research has focusedon polyimide composites to achieve an acceptable balance between thermalstability, solvent resistance, and toughness for these high performanceapplications. Still the maximum temperatures for use of the polyimidecomposites, such as those formed from PMR-15, can only be used attemperatures below about 600°-625° F. (315°-330° C.), since they haveglass transition temperatures of about 690° F. (365° C.). PMR compositesare usable in long term service (50,000 hours) at about 350° F. (170°C.). They can withstand temperatures up to about 600° F. (315° C.) forup to about five hundred hours.

PMR-15 prepregs, however, suffer significant processing limitations thathinder their adoption because the prepreg has a mixture of the unreactedmonomer reactants on the fiber-reinforcing fabric, making them sensitiveto changes in temperature, moisture, and other storage conditions, whichcause the prepregs to be at different stages of cure. The resultingcomposites have varying, often unpredictable properties. Aging these PMRprepregs even in controlled environments can lead to problems. Thereactants on the prepreg are slowed in their reaction by keeping themcold, but the quality of the prepreg depends on its absolute age and onits prior storage and handling history. And, the quality of thecomposite is directly proportional to the quality of the prepregs. Inaddition, the PMR monomers are toxic or hazardous (especially MDA),presenting health and safety concerns for the workforce. Achievingcomplete formation of stable imide rings in the PMR composites remainsan issue. These and other problems plague PMR-15 composites.

The commercial long chain polyimides also present significant processingproblems. AVIMID-N and AVIMID-KIII (trademarks of E. I. duPont deNemours) resins and prepregs differ from PMRs because they do notinclude aliphatic chain terminators which the PMRs use to controlmolecular weight and to retain solubility of the PMR intermediatesduring consolidation and cure. Lacking the chain terminators, theAVIMIDs can chain extend to appreciable molecular weights. To achievethese molecular weights, however, the AVIMIDs (and their LARC cousins)rely on the melting of crystalline powders to retain solubility or, atleast, to permit processing. It has proven difficult to use the AVIMIDsin aerospace parts both because of their crystalline melt intermediatestage and the PMR plague that these AVIMID prepregs also suffer aging.

So, research continues and is now turning toward soluble systems likethose we described in our earlier patents, includingacetylenic-terminated AVIMID-KIII prepregs of the Hergenrother(NASA-Langley) type. For these soluble systems, many different polyimidesulfone compounds have been synthesized to provide unique properties orcombinations of properties. For example, Kwiatkowski and Brode (U.S.Pat. No. 3,839,287) synthesized monofunctional, maleic-capped linearpolyarylimides. Holub and Evans (U.S. Pat. No. 3,729,446) synthesizedsimilar maleic or nadic-capped, imido-substituted polyestercompositions.

For imides and many other resin backbones we have shown surprisinglyhigh glass transition temperatures, reasonable processing parameters andconstraints for the prepregs, and desirable physical properties for thecomposites by using soluble oligomers having difunctional caps,especially those with nadic caps. Linear oligomers of this type includetwo crosslinking functionalities at each end of the resin chain topromote crosslinking upon curing. Linear oligomers are "monofunctional"when they have one crosslinking functionality at each end. The preferredoligomers from our earlier research were "difunctional," because theyhad two functional groups at each end. Upon curing, the crosslinkingfunctionalities provide sites for chain extension. Because thecrosslinks were generally the weakest portions of the resultingcomposite, we improved thermo-oxidative stability of the composites byincluding two crosslinks at each junction. We built in redundancy, then,at each weak point. We maintained solubility of the reactants and resinsusing, primarily, phenoxyphenyl sulfone chemistries. Our work during thepast fifteen years across a broad range of resin types or chemicalfamilies is described in the following, forty-nine United States Patents(all of which we incorporate by reference):

    ______________________________________                                        INVENTOR PATENT   TITLE         ISSUE DATE                                    ______________________________________                                        Lubowitz et al.                                                                        4,414,269                                                                              Solvent Resistant                                                                           November 9, 1983                                                Polysulfone and                                                               Polyethersulfone                                                              Composites                                                  Lubowitz et al.                                                                        4,476,184                                                                              Thermally Stable Poly-                                                                      October 9, 1984                                                 sulfone Compositions                                                          for Composite                                                                 Structures                                                  Lubowitz et al.                                                                        4,536,559                                                                              Thermally Stable                                                                            August 20, 1985                                                 Polyimide Polysulfone                                                         Compositions for                                                              Composite Structures                                        Lubowitz et al.                                                                        4,547,553                                                                              Polybutadiene Modi-                                                                         October 15, 1985                                                fied Polyester                                                                Compositions                                                Lubowitz et al.                                                                        4,584,364                                                                              Phenolic-Capped                                                                             April 22, 1986                                                  Imide Sulfone                                                                 Resins                                                      Lubowitz et al.                                                                        4,661,604                                                                              Monofunctional Cross-                                                                       April 28, 1987                                                  linking Imidophenols                                        Lubowitz et al.                                                                        4,684,714                                                                              Method for Making                                                                           August 4, 1987                                                  Polyimide Oligomers                                         Lubowitz et al.                                                                        4,739,030                                                                              Difunctional End-Cap                                                                        April 19, 1988                                                  Monomers                                                    Lubowitz et al.                                                                        4,847,333                                                                              Blended Polyamide                                                                           July 25, 1989                                                   Oligomers                                                   Lubowitz et al.                                                                        4,851,495                                                                              Polyetherimide                                                                              July 25, 1989                                                   Oligomers                                                   Lubowitz et al.                                                                        4,851,501                                                                              Polyethersulfone                                                                            July 25, 1989                                                   Prepregs, Composites,                                                         and Blends                                                  Lubowitz et al.                                                                        4,868,270                                                                              Heterocycle Sulfone                                                                         September 19, 1989                                              Oligomers and Blends                                        Lubowitz et al.                                                                        4,871,475                                                                              Method for Making                                                                           October 3, 1989                                                 Polysulfone and                                                               Polyethersulfone                                                              Oligomers                                                   Lubowitz et al.                                                                        4,876,328                                                                              Polyamide Oligomers                                                                         October 24, 1989                              Lubowitz et al.                                                                        4,935,523                                                                              Crosslinking  June 19, 1990                                                   Imidophenylamines                                           Lubowitz et al.                                                                        4,958,031                                                                              Crosslinking  September 18, 1990                                              Nitromonomers                                               Lubowitz et al.                                                                        4,965,336                                                                              High Performance                                                                            October 23, 1990                                                Heterocycle Oligomers                                                         and Blends                                                  Lubowitz et al.                                                                        4,980,481                                                                              Pyrimidine-Based                                                                            December 25, 1990                                               End-Cap Monomers                                                              and Oligomers                                               Lubowitz et al.                                                                        4,981,922                                                                              Blended Etherimide                                                                          January 1, 1991                                                 Oligomers                                                   Lubowitz et al.                                                                        4,985,568                                                                              Method of Making                                                                            January 15, 1991                                                Crosslinking                                                                  Imidophenyl-amines                                          Lubowitz et al.                                                                        4,990,624                                                                              Intermediate  February 5, 1991                                                Anhydrides Useful for                                                         Synthesizing                                                                  Etherimides                                                 Lubowitz et al.                                                                        5,011,905                                                                              Polyimide Oligomers                                                                         April 30, 1991                                                  and Blends                                                  Lubowitz et al.                                                                        5,066,541                                                                              Multidimensional                                                                            November 19, 1991                                               Heterocycle Sulfone                                                           Oligomers                                                   Lubowitz et al.                                                                        5,071,941                                                                              Multidimensional                                                                            December 10, 1991                                               Ether Sulfone                                                                 Oligomers                                                   Lubowitz et al.                                                                        5,175,233                                                                              Multidimensional                                                                            December 29, 1991                                               Ester or Ether                                                                Oligomers with                                                                Pyrimidinyl End Caps                                        Lubowitz et al.                                                                        5,082,905                                                                              Blended Heterocycles                                                                        January 21, 1992                              Lubowitz et al.                                                                        5,087,701                                                                              Phthalimide Acid                                                                            February 11, 1992                                               Halides                                                     Lubowitz et al.                                                                        5,104,967                                                                              Amideimide Oligomers                                                                        April 14, 1992                                                  and Blends                                                  Lubowitz et al.                                                                        5,109,105                                                                              Polyamides    April 28, 1992                                Lubowitz et al.                                                                        5,112,939                                                                              Oligomers Having                                                                            May 12, 1992                                                    Pyrimidinyl End Caps                                        Lubowitz et al.                                                                        5,115,087                                                                              Coreactive Imido                                                                            May 19, 1992                                                    Oligomer Blends                                             Lubowitz et al.                                                                        5,116,935                                                                              High Performance                                                                            May 26, 1992                                                    Modified Cyanate                                                              Oligomers and Blends                                        Lubowitz et al.                                                                        5,120,819                                                                              High Performance                                                                            June 9, 1992                                                    Heterocycles                                                Lubowitz et al.                                                                        5,126,410                                                                              Advanced Heterocycle                                                                        June 30, 1992                                                   Oligomers                                                   Lubowitz et al.                                                                        5,144,000                                                                              Method for Forming                                                                          September 1, 1992                                               Crosslinking                                                                  Oligomers                                                   Lubowitz et al.                                                                        5,151,487                                                                              Method of Preparing a                                                                       October 1, 1992                                                 Crosslinking Oligomer                                       Lubowitz et al.                                                                        5,155,206                                                                              Amideimide    October 13, 1992                                                Oligomers, Blends                                                             and Sizings for                                                               Carbon Fiber                                                                  Composites                                                  Lubowitz et al.                                                                        5,159,055                                                                              Coreactive Oligomer                                                                         October 27, 1992                                                Blends                                                      Lubowitz et al.                                                                        5,175,234                                                                              Lightly-Crosslinked                                                                         December 29, 1992                                               Polyimides                                                  Lubowitz et al.                                                                        5,175,304                                                                              Halo- or Nitro-                                                                             December 29, 1992                                               Intermediates Useful                                                          for Synthesizing                                                              Etherimides                                                 Lubowitz et al.                                                                        5,198,526                                                                              Heterocycle Oligomers                                                                       March 30, 1993                                                  with Multidimensional                                                         Morphology                                                  Lubowitz et al.                                                                        5,210,213                                                                              Multidimensional                                                                            May 11, 1993                                                    Crosslinkable                                                                 Oligomers                                                   Lubowitz et al.                                                                        5,216,117                                                                              Amideimide Blends                                                                           June 1, 1993                                  Lubowitz et al.                                                                        5,227,461                                                                              Extended Difunctional                                                                       July 13, 1993                                                   End-Cap Monomers                                            Lubowitz et al.                                                                        5,239,046                                                                              Amideimide Sizing                                                                           August 24, 1993                                                 For Carbon Fiber                                            Lubowitz et al.                                                                        5,268,519                                                                              Lightly Crosslinked                                                                         December 7, 1993                                                Etherimide Oligomers                                        Lubowitz et al.                                                                        5,286,811                                                                              Blended Polyimide                                                                           February 15, 1994                                               Oligomers and Method                                                          of Curing Polyimides                                        Lubowitz et al.                                                                        5,328,964                                                                              Blended Polyimide                                                                           July 12, 1994                                                   Oligomers                                                   Lubowitz et al.                                                                        5,344,894                                                                              Polyimide Oligomers                                                                         September 6, 1994                                               and Blends                                                  ______________________________________                                    

The heterocycles (i.e., oxazoles, thiazoles, or imidazoles) use aprocessing principle more akin to the AVIMIDs than the phenoxyphenylsulfone solubility principle of our other resins. The heterocycles havepoor solubility, even with our "sulfone" chemistries, but they at leastform liquid crystals or soluble crystals in strong acids. To producenon-crystalline (amorphous) composites, we capitalize on the ability ofour heterocycles to melt at the same temperature range as the cure andpromote crosslinking in the melt. With relatively low molecular weight,capped, heterocycle oligomers, we can autoclave process these materials.Autoclave processing is a significant achievement for these heterocycleswhich present to the industry, perhaps, the most challenging problems.The polybenzoxazoles we produced, in addition, are useful attemperatures up to about 750°-775° F. (400°-413° C.), since they haveglass transition temperatures of about 840° F. (450° C.). We describemultifunctional heterocycle and heterocycle sulfones in copending U.S.patent application Ser. No. 08/327,180 filed Oct. 21, 1994 now U.S. Pat.No. 5,594,089 which we incorporate by reference.

Some aerospace applications need composites which have even higher usetemperatures than these polybenzoxazoles while maintaining toughness,solvent resistance, ease of processing, formability, strength, andimpact resistance. Southcott et al. discuss the problems of the priorart imide systems and the advantages of our soluble monofunctional anddifunctional nadic-capped imide systems in the article: Southcott etal., "The development of processable, fully imidized, polyimides forhigh-temperature applications," 6 High Perform. Polym., 1-12 (U.K.1994). For these extremely demanding requirements, our multidimensionaloligomers (i.e., oligomers that have three or more arms extending from acentral organic hub to yield three-dimensional morphology) have superiorprocessing parameters over more conventional, linear oligomers thatmight produce composites having these high thermal stabilities. Ourmultidimensional oligomers can satisfy the thermal stabilityrequirements and can be processed at significantly lower temperatures.Upon curing the end caps, the multidimensional oligomers crosslink sothat the thermal resistance of the resulting composite is markedlyincreased with only a minor loss of stiffness, matrix stress transfer(impact resistance), toughness, elasticity, and other mechanicalproperties. We can achieve glass transition temperatures above 950° F.(510° C.) with composites cured from our difunctional multidimensionaloligomers (which we call "star-burst" oligomers). Of course, a fullrange of use temperatures are possible by selecting the hubs (whichusually is an aromatic moiety), the backbone monomers used in the arms,end caps, and number of crosslinking functionalities per cap.

We now believe we can achieve even better properties in advancedcomposites by including an even higher number of crosslinkingfunctionalities than the mono- or difunctional systems of the linear ormultidimensional resins discussed in our earlier patents or patentapplications. The higher density of crosslinks provide redundancy atthose locations in the macromolecular, cured composite which are mostsusceptible to thermal degradation.

SUMMARY OF THE INVENTION

The present invention provides oligomers that produce advancedcomposites with high thermomechanical stability and highthermo-oxidative stability by using four crosslinking functionalities(i.e., unsaturated hydrocarbon moieties) at each end of the oligomer.Upon curing, the crosslinking functionalities on adjacent oligomers formfour parallel linkages in the composite to provide the improvedstabilities. The oligomers, however, retain the preferred properties ofour difunctional oligomers with respect to handling and processing. Thecomposites we form from our multiple chemically functional oligomershave even higher thermal stabilities for comparable backbone andmolecular weight and have higher compressive strengths than ourcomposites formed using our mono- or difunctional oligomers. Thepreferred oligomers generally have soluble, stable, fully aromaticbackbones. Sulfone (--SO₂ --) or other electronegative linkages ("L")selected from the group consisting of --SO₂ --, --S--, --CO--, --(CF₃)₂C--, or --(CH₃)₂ C-- in the backbones between aromatic groups provideimproved toughness for the composites and provide the improvedsolubility for the oligomers that is so important to effectiveprocessing. A typical backbone usually has repeating units of thegeneral formula:

    --Ar--O--Ar--L--Ar--O--Ar--

wherein Ar is an aromatic radical (and preferably phenylene) and L is anelectronegative linkage as previously defined. In this description wewill refer to "L" as a sulfone. Any of the identified electronegativegroups can be substituted, however, for --SO₂ --.

The four caps at each end of the backbone of a linear oligomer or at theend of each arm of a multidimensional oligomer provide areas of highstiffness in the composite product. These stiff, highly crosslinkedareas are relatively lightly interspersed in a thermoplastic matrix,yielding superior composites for aerospace applications. Generally,highly crosslinked matrices yield high compressive strength but thecomposites are brittle. Thermoplastics are tough but have significantlylower compressive strengths. In the present invention, the multiplechemically functional end caps produce highly crosslinked micelleswithin the resin matrix equivalent in size roughly to colloidalparticles. These micelles enhance resin interactions that are vital toachieve high compressive strengths by, we believe, adsorbing the linearpolymer chains onto the micelle surfaces and linking multiple linearchains. Thus, we achieve thermoplastics with high compressive strength.

Our preferred four functional crosslinkable, thermoplastic oligomers areformed by reacting in the appropriate stoichiometry an end cap monomerwith one or more reactants selected to form the predominant andcharacteristic backbone linkage by which we identify the nature of theresulting oligomer (i.e., ether, ester, imide, amide, amideimide,carbonate, sulfone, etc.) in a suitable solvent under an inertatmosphere. The soluble oligomers generally have a weight averagemolecular weight (MW) of between about 5,000 and 40,000, preferablybetween about 5,000-15,000, and more preferably between 10,000-15,000.We generally try to synthesize oligomers to the highest MWs we canprovided that the oligomers remain soluble in conventional processingsolvents. In these ranges, the oligomer will have thermoplasticcharacteristics.

Multidimensional oligomers include an organic hub and three or moresubstantially identical radiating arms, each arm terminating with aresidue of a multifunctional crosslinking end cap monomer. Suitable hubsradicals are described in the patents we earlier incorporated byreference with respect to our monofunctional and difunctional oligomerresearch, although we prefer a 1,3,5-phenylene (i.e., benzenetriyl). Formultiple chemically functional end caps, we prefer linear morphologyover multidimensional morphology because linear systems are easier toprepare to have significant MW in the backbone between the caps. Suchhigh MW better allows the micelles that form on crosslinking to providetheir advantages to the compressive strength.

We can also blend our linear or multidimensional oligomers as we didwith the difunctional systems. A blend might include a linear oligomerwith a comparable linear polymer, a multidimensional oligomer with amultidimensional polymer, a linear oligomer with a multidimensionaloligomer, or the like. By "polymer," we mean a resin that does notinclude the crosslinking functionalities of our oligomers. By"oligomer," we mean any molecular weight moiety that includescrosslinking functionalities at its ends to allow it to react(chain-extend) to increase the effective molecular weight when theoligomer cures to form a composite. By "crosslinking functionality," wemean a terminating, unsaturated hydrocarbon group that can be thermallyor chemically activated when the resin is in the melt to covalently bondto an adjacent, corresponding moiety on another oligomer.

A blend will generally include substantially equimolar amounts of theoligomer and a polymer. The polymer will generally have the samebackbone structure and MW as the oligomer (or it might have a higher MWsince the oligomer will chain-extend upon curing). We prepare blends bymixing miscible solutions of the oligomers and polymers.

Prepregs and composites are the most preferred products of the oligomersand blends, although we can also prepare varnishes, films, and coatings.Some oligomers are also suitable as sizings for carbon fibers. We canalso prepare PMR-analogs where reactive monomers are prepregged. By"composite," we mean the product of curing and consolidating theoligomers to produce high MW chains through crosslinking, chainextension.

BEST MODE CONTEMPLATED FOR CARRYING OUT THE INVENTION

We will first discuss elements that are relatively independent of theresin chemistries before discussing the details of the end cap monomersand, finally, the individual resin chemistries.

1. Overriding Principles and Common Features

The weight average molecular weight (MW) of the multiple chemicallyfunctional oligomers of the present invention should providethermoplastic character to the oligomer and generally should be between5,000 and 40,000, but preferably between about 10,000 and 35,000, andstill more preferably between 15,000 and 30,000. Such weights areusually achievable by using between 1-20 molecules of each reactant inthe backbone (with two caps, of course, for linear systems) and oftenbetween 1-5 molecules of each reactant, as those of ordinary skill willrecognize. We seek to synthesize the highest MW that we can which willremain soluble and easy to process. We seek the highest MW that we cansuccessfully synthesize repeatedly and reliably. Within the preferredrange, the oligomers are relatively easy to process to form compositesthat are tough, have impact resistance, possess superiorthermomechanical properties, and have superior thermo-oxidativestability. When oligomers having MW less than about 5,000 are cured bycrosslinking, the thermosetting character of the material is increasedso that the ability to thermoform the product may be drastically reducedor eliminated.

Solubility of the oligomers becomes an increasing problem as chainlength increases. Therefore, from a solubility standpoint, we prefershorter chains for processing, if the resulting composites retain thedesired properties. That is, the chains should be long enough to yieldthermoplastic characteristics to the composites but short enough to keepthe oligomers soluble during the reaction sequence.

We represent the oligomers of the present invention by the formulae:ξ--R₄ --ξ for linear oligomers or ∂.paren open-st.A--ξ)_(w) formultidimensional oligomers wherein w=3 or 4; ξ is the residue of amultiple chemically functional end cap monomer; ∂ is a "w" valent,multidimensional organic hub; A is a multidimensional arm, and R₄ is adivalent, linear, aromatic, aliphatic, or alicydic organic radical.Preferred backbones (R₄ or A) are aromatic chains to provide the highestthermal stability where the predominant backbone linkages are selectedfrom the group consisting of:

imide

amideimide

etherimide

ether

ether sulfone

arylene sulfide (PPS)

ester

ester sulfone

amide

carbonate

cyanate ester and

esteramide.

We use "linear" to mean generally in a line or in one plane and todistinguish readily from "multidimensional" where we produce 3-Dsystems. "Linear" systems are not perfectly straight, because of carbonchemistry. "Linear" systems are the conventional morphology for polymerchemistry resulting from "head-to-tail" condensation of the reactants toform a chain. "Multidimensional" oligomers include a hub from whichthree or more arms extend.

We seek thermally stable oligomers suitable for high temperatureadvanced composites. Such oligomers generally include a high degree ofaromatic groups. The stable aromatic bond energies produce an oligomerwith outstanding thermal stability. Acceptable toughness and impactresistance is gained through selection of the linkages within the linearchains or in the arms of aromatic groups radiating in ourmultidimensional oligomers from the central aromatic hub. Thesetoughening linkages are ethers, esters, and the electronegative("sulfone") linkages (L) selected from the group consisting of --CO--,--SO₂ --, --S--, --(CF₃)₂ C--, or --(Me₃)₂ C--, that we earlierdiscussed. Generally, --CO-- and --SO₂ -- groups are preferred for cost,convenience, and performance. The group --S--S-- should be avoided,since it is too thermally labile.

We retain processability in our oligomers by keeping them soluble inconventional processing solvents through the inclusion of solublesegments in their backbones. The backbones generally are formed bycondensing two monomer reactants A_(e) and B_(e) with chain extensionquenched with our multiple chemically functional end cap monomers. A_(e)is an acid monomer reactant and B_(e) is a base. A_(e) and B_(e) producethe characteristic backbone linkage --δ_(e) -- for which we name theoligomer. The linear oligomers have the general formula: ##STR4##wherein m typically is a small integer between 0 and 20. To achievesolubility, we prefer that at least one of A_(e) or B_(e) include asoluble repeating unit of the formula:

    --.O slashed.--L--.O slashed.-- or

    --.O slashed.--O--.O slashed.--L--.O slashed.--O--.O slashed.--

wherein .O slashed.=phenylene and

    L=--SO.sub.2 --, --S--, --CO--, --(CF.sub.3).sub.2 C--, or --(CH.sub.3)C--.

Generally, the A_(e) and B_(e) use our phenoxyphenyl sulfone solubilityprinciple. By analogy, we include the same principles in ourmultidimensional oligomers.

In multidimensional oligomers of all resin types, the organic hub (∂)includes a plurality of rays or spokes radiating from the hub in thenature of a star to provide multidimensional crosslinking throughsuitable terminal groups with a greater number (i.e. higher density) ofcrosslinking bonds than linear arrays provide. Usually the hub will havethree radiating chains to form a "Y" pattern. In some cases, we use fourchains. Including more chains may lead to steric hindrance as the hub istoo small to accommodate the radiating chains. We prefer atrisubstituted phenyl hub (i.e., a benzenetriyl) with the chains beingsymmetrically placed about the hub.

Although the preferred aromatic moieties are aryl groups (such asphenylene, biphenylene, and naphthylene), other aromatic groups can beused, if desired, since the stabilized aromatic bonds will also probablyprovide the desired thermal stability. For example, we can use azaline(melamine) ##STR5## or pyrimidine ##STR6## groups.

We make prepregs from the oligomers of the present invention by theconventional method of impregnating a suitable fabric or otherreinforcement with a mixture of the oligomer and a solvent. We can addsuitable coreactants to the solvent when preparing prepregs, especiallythose having maleic end caps, as taught in our earlier patents.

We can also prepare prepregs for composites, especially for PPS resins,by interleaving layers of fabric with layers of a resin film comprisingan oligomer or blend, and then subjecting the resultant stack ofinterleaved materials to heat and pressure sufficient to "flow" theoligomer into the fabric and to crosslink the oligomer to form thefiber-reinforced composite. According to a further alternative, we canspin the oligomer into fibers, and weave these fibers with fibers ofreinforcing material to produce a prepreg. This prepreg is cured in amanner comparable to the method of forming a composite from interleavedoligomer film and fabric layers. Finally, especially for PPS resins, wecan use the powder impregnation technology common for prepregging PPS.

We cure the conventional prepregs by conventional vacuum bag autoclavetechniques to crosslink the end caps. Temperatures suitable for curingare in the range of 150°-650° F. (65°-345° C.). The resulting product isa cured, thermally stable, solvent-resistant composite. Post-curing toensure essentially complete addition polymerization through thefour-caps likely is desirable if not essential. The composites havestiff, highly crosslinked micelles dispersed in a thermoplastic matrix.The crosslinked oligomer may also be used as an adhesive without curing.Such adhesives may be filled, if desired.

Blended oligomers typically comprise a substantially equimolar amount ofthe oligomer and a comparable polymer that is incapable of crosslinkingwith the selected crosslinkable oligomers. These blends merge thedesired properties of crosslinking oligomers with those of thenoncrosslinking polymer to provide tough, yet processable, resin blends.The comparable polymer is usually synthesized by condensing the samemonomer reactants of the crosslinking oligomer and quenching thepolymerization with a suitable terminating group. The terminating grouplacks the hydrocarbon unsaturation common to the oligomer's end capmonomers. In this way, the comparable polymer has the identical backboneto that of the crosslinkable oligomer but does not have thecrosslinkable end caps. Generally the terminating group will be a simpleanhydride (such as benzoic anhydride), phenol, or benzoyl acid chlorideto quench the polymerization and to achieve a MW for the comparablepolymer substantially equal to or initially higher than that of thecrosslinkable oligomer.

We can prepare blends by combining the oligomers of the presentinvention with corresponding linear or multidimensional, monofunctionalor difunctional oligomers of our earlier patents or our copending patentapplications. We can blend three or more components. We can blenddifferent resins (i.e., advanced composite blends corresponding to thoseblends described in U.S. patent application Ser. No. 07/619,677 orcoreactive oligomer blends corresponding to these blends described,e.g., in U.S. Pat. Nos. 5,115,087 and 5,159,055).

With blends, we can increase the impact resistance of imide compositesover the impact resistance of pure imide resin composites withoutsignificantly reducing the solvent resistance. A 50--50 molar blend ofoligomer and polymer is what we prefer and is formed by dissolving thecapped oligomer in a suitable first solvent, dissolving the uncappedpolymer in a separate portion of the same solvent or in a second solventmiscible with the first solvent, mixing the two solvent solutions toform a lacquer, and applying the lacquer to fabric in a conventionalprepregging process (often called "sweep out").

Although the polymer in the blend often originally has the same lengthbackbone (i.e., MW) as the oligomer, we can adjust the properties of thecomposite formed from the blend by altering the ratio of MWs for thepolymer and oligomer. It is probably nonessential that the oligomer andpolymer have identical repeating units, but that the oligomer andpolymer merely be compatible in the mixed solution or lacquer prior tosweeping out the blend as a prepreg. Of course, if the polymer andoligomer have identical backbones, compatibility in the blend is morelikely to occur.

Solvent resistance may decrease markedly if the comparable polymer isprovided in large excess to the crosslinkable oligomer in the blend.

The blends might be semi-interpenetrating networks (i.e., IPNs) of thegeneral type described by Egli et al. "Semi-Interpenetrating Networks ofLARC-TPI" available from NASA-Langley Research Center or in U.S. Pat.No. 4,695,610.

We prepare prepregs of the oligomers or blends by conventionaltechniques. While woven fabrics are the typical reinforcement, thefibers can be continuous or discontinuous (in chopped or whisker form)and may be ceramic, organic, carbon (graphite), or glass, as suited forthe desired application.

As shorthand, we may use the term "multifunctional" to describeoligomers having four chemically functional groups in each end cap.

Although para isomers are shown for the reactants and the oligomers (andpara isomers are preferred), other isomers of the monomer reactants arepossible. Meta-isomers may be used to enhance solubility and to achievemelt-flow at lower temperatures, thereby yielding more soluble oligomerswith enhanced processing characteristics. The isomers (para- and meta-)may be mixed. Substituents may create steric hindrance problems insynthesizing the oligomers or in crosslinking the oligomers into thefinal composites, but substituents can be used if these problems can beavoided.

Therefore, each aryl group for the monomer reactants may includesubstituents for the replaceable hydrogens, the substituents beingselected from the group consisting of halogen, alkyl groups having 1-4carbon atoms, and alkoxy groups having 1-4 carbon atoms. We preferhaving no substituents.

Our oligomers and blends are heat-curable resin systems. By the term"heat-curable resin system" we mean a composition containing reactivemonomers, oligomers, and/or prepolymers which will cure at a suitablyelevated temperature to an infusible solid, and which compositioncontains not only the aforementioned monomers, oligomers, etc., but alsosuch necessary and optional ingredients such as catalysts, co-monomers,rheology control agents, wetting agents, tackifiers, tougheners,plasticizers, fillers, dyes and pigments, and the like, but devoid ofmicrospheres or other "syntactic" fillers, continuous fiberreinforcement, whether woven, non-woven (random), or unidirectional, andlikewise devoid of any carrier scrim material, whatever its nature.

By the term "syntactic foam" we mean a heat-curable resin system whichcontains an appreciable volume percent of preformed hollow beads or"microspheres." Such foams are of relatively low density, and generallycontain from 10 to about 60 weight percent of microspheres, and have adensity, upon cure, of from about 0.50 g/cm³ to about 1.1 g/cm³ andpreferably have loss tangents at 10 GHz as measured by ASTM D 2520 of0.008 or less. The microspheres may consist of glass, fused silica, ororganic polymer, and range in diameter from 5 to about 200 μm, and havedensities of from about 0.1 g/cm³ to about 0.4 g/cm³ to about 0.4 g/cm³.

By the term "matrix resin" we mean a heat-curable resin system whichcomprises the major part of the continuous phase of the impregnatingresin of a continuous fiber-reinforced prepreg or composite. Suchimpregnating resins may also contain other reinforcing media, such aswhiskers, microfibers, short hopped fibers, or microspheres. Such matrixresins are used to impregnate the primary fiber reinforcement at levelsof between 10 and 70 weight percent, generally from 30 to 40 weightpercent. Both solution and/or melt impregnation techniques may be usedto prepare fiber reinforced prepregs containing such matrix resins. Thematrix resins may also be used with chopped fibers as the major fiberreinforcement, for example, where pultrusion techniques are involved.

If the linear or multidimensional oligomers include Schiff base orheterocycle linkages (oxazoles, thiazoles, or imidazoles), thecomposites may be conductive or semiconductive when suitably doped. Thedopants are preferably selected from compounds commonly used to dopeother polymers, namely, (1) dispersions of alkali metals (for highactivity) or (2) strong chemical oxidizers, particularly alkaliperchlorates (for lower activity). We do not recommend arsenic compoundsand elemental halogens, while active dopants, are too dangerous forgeneral usage.

The dopants apparently react with the oligomers or polymers to formcharge transfer complexes. N-type semiconductors result from doping withalkali metal dispersions. P-type semiconductors result from doping withelemental iodine or perchlorates. We recommend adding the dopant to theoligomer or blend prior to forming the prepreg.

While research into conductive or semiconductive polymers has beenactive, the resulting compounds (mainly polyacetylenes, polyphenylenes,and polyvinylacetylenes) are unsatisfactory for aerospace applicationsbecause the polymers are unstable in air; unstable at high temperatures;brittle after doping; toxic because of the dopants; or intractable.These problems are overcome or significantly reduced with the conductiveoligomers of the present invention.

While conventional theory holds that semiconductive polymers should have(1) low ionization potentials, (2) long conjugation lengths, and (3)planar backbones, there is an inherent trade-off between conductivity,toughness, and ease of processing, if these constraints are followed. Toovercome the processing and toughness shortcomings common with Schiffbase, oxazole, imidazole, or thiazole polymers, the oligomers of thepresent invention generally include "sulfone" linkages interspersedalong the backbone providing a mechanical swivel for the rigid,conductive segments of the arms.

Having described the common features, we next turn to the end capmonomers that characterize the structure and performance of theoligomers of the present invention.

2. The Multiple Chemically Functional End Cap Monomers

End cap monomers of the present invention include organic compounds ofthe formula: ##STR7## wherein .O slashed.=phenylene; ##STR8##

R₃ =independently, any of lower alkyl, lower alkoxy, aryl, aryloxy, orhydrogen;

G=--CH₂ --, --S--, --O--, or --(Me)₂ C--;

T=allyl or methallyl;

Me=methyl; ##STR9##

X=halogeno, and preferably chlorine;

R=a divalent residue of a diol or nitrophenol; and

R₈ =the residue of an amino/acid (preferably, phenylene).

Preferably, i=2 so that the monomers have four crosslinkingfunctionalities (i.e., the hydrocarbon unsaturation at the chain end).Other organic unsaturation, however, also can be used. The end cappingfunctionality (E) can also be a cyanate or vinyl selected from:##STR10## wherein R₃ =hydrogen, lower alkyl, lower aryl, lower alkoxy,or lower aryloxy.

Ethynyl, trimethylsilylethynyl, phenylethynyl, or benzyl cyclobutane endcaps may also be used, if desired. These end caps will probably allowcuring at lower temperatures, and will probably produced composites oflower thermal stability.

Preferred end cap monomers for forming oligomers with multiplechemically functional oligomers are phenols having the formula:##STR11##

--.O slashed.--=phenylene;

ROH=--.O slashed.--OH or --.O slashed.--L--.O slashed.--OH;

R₁ =any of lower alkyl, lower alkoxy, aryl, substituted alkyl,substituted aryl (including in either case hydroxyl or halo-substituentson replaceable hydrogens), aryloxy, or halogen;

L=--SO₂ --, --CO--, --S--, --(CF₃)₂ C--, or --(Me)₂ C--;

i=1 or 2;

j=0, 1, or 2;

G=--CH₂ --, --S--, --O--, --SO₂ --, --(Me)CH--, or --(Me)₂ C--; and

Me=methyl (i.e., --CH₃).

Preferably, j=0, so there are no R₁ substituents. Also, preferably, i=2,so each phenol monomer has four nadic functionalities. These phenol endcap monomers link to the backbone with an ether or ester linkage. Thenadic caps are illustrative of the capping moieties as those skilled inthe art will recognize based in our issued patents, copendingapplications, and the remainder of this specification.

The phenol monomers can be made by several mechanisms. For example, thehalide end cap ##STR12## is condensed with the diol HO--.O slashed.--SO₂--.O slashed.--OH or HO--.O slashed.--OH to yield the desired cap. Thehalide end cap is formed by condensing: ##STR13## While a1,3,5-halodiaminobenzene is shown, and this isomer is preferred, the1,2,4-halodiaminobenzene isomer might also be used.

The acid or acid halide end cap monomer can be made in a similar waysubstituting, however, a diaminobenzoic acid for the halodiaminobenzene.Again, we prefer the 1,3,5-isomer, but note that the 2,3-, 2,4-, 2,5-,3,4-, and 3,5-diaminobenzoic acid isomers are known. The 1,3,5-isomerprovides maximum spacing between groups, which likely is important. Anextended acid halide monomer can be made by reacting: ##STR14## toprotect the amines (probably using the 2,4-diaminonitrobenzene isomer),extracting the nitro functionality with HO--.O slashed.--COOH to yield:##STR15## saponifying the imides to recover the amines, recondensing theamines with the acid halide described above, and, finally, convertingthe carboxylic acid to the acid halide, yielding: ##STR16##

Alternatively, an acid halide end cap monomer of the formula: ##STR17##is made by condensing (Z)₂ --.O slashed. with a dibasic aromaticcarboxylic acid in the Friedel-Crafts reaction.

It may also be possible to make an acid halide end cap of the formula:##STR18## or a corresponding phenol by condensing the halide monomerwith HO--.O slashed.--COX in the Ullmann ether synthesis over a Cucatalyst. Here, the halide monomer should be dripped into the diol, ifmaking the extended phenol.

For the preparation of imides where an anhydride is an importantfunctionality for the end cap monomer, we extend the four functionalphenol monomer of formula (II) either with nitrophthalic anhydride##STR19## or phthalic anhydride acid chloride (i.e., trimelleitic acidhalide anhydride) to form an ether or ester analog having an activeanhydride. The analog, then, has the formula: ##STR20## wherein Q=etheror ester. We can make another extended anhydride by condensing:##STR21## to yield: ##STR22## Extended anhydrides link to the backbonewith an imide linkage.

For the preparation of heterocycles, esters, or other oligomers, we canprepare another extended acid monomer by condensing nitrobenzoic acid(or the acid halide) with the extend phenol monomer of formula (II) toyield: ##STR23## Alternatively, we can condensed the anhydride offormula (IV A) or (IV B) with an amino/acid, like aminobenzoic acid, toyield: ##STR24## self-condensation of the amino/acid needs to beavoided, so it should be added dropwise to the anhydride. The acids canbe readily converted with SOCl₂ to their acid halide (--COX) analog. Theacid or acid halide end cap monomers link to the backbone with ester,oxazole, or imidazole linkages, for example.

We can prepare amine extended caps by reacting the halide monomer withaminophenol to yield: ##STR25## or aminobenzoic acid with the extendedphenol monomer (taking care to avoid self-condensation of theamino/acid) to yield: ##STR26##

We can prepare the amine end cap monomer by converting a --COXfunctionality to an amine through the acid amide in the presence ofammonia, as described in U.S. Pat. No. 4,935,523.

The remainder of this specification will usually illustrate only thenadic end cap monomers, but those skilled in the art will understandthat any of the other crosslinking functionalities could substitute forthe nadic group.

A pyrimidine ring can be substituted for the phenylene ring in formula(I) to form end cap monomers analogous to those described in our U.S.Pat. Nos. 4,980,481 and 5,227,461. The aromatic character of thepyrimidine ring should provide substantially the same benefits as thephenylene ring. The thermo-oxidative stability of the resultingcomposites, however, might be somewhat less than that achieved for thephenyl end cap monomers. The pyrimidine precursors are described in U.S.Pat. Nos. 3,461,461 and 5,227,461. The compound: ##STR27## permits halo-pyrimidine end cap monomers for use in ether syntheses. Thesehalo-pyrimidine caps have the formula: ##STR28##

From these examples of extended monomers, those skilled in the art willrecognize the wide range of monomers that might be used to introducemultifunctional capping. Furthermore, if stepwise synthetic pathways areused, the extended caps do not necessarily need to be separatelysynthesized and recovered (see, e.g., the ether and ester syntheseswhich follow).

We will next discuss the principal chemical families of resins that wecan prepare using the multiple chemically functional ("multifunctional")end cap monomers. These multiple chemically functional oligomers areanalogous to the monofunctional and difunctional oligomers described inour issued patents and copending patent applications.

3. Imide Oligomers

We preferably prepare our imide oligomers by condensing suitablediamines and dianhydrides with an extended anhydride end cap monomer offormula (IV A) or (IV B) or an extended amine end cap monomer of formula(VII) or (VIII) in a suitable solvent in an inert atmosphere. Thesynthesis is comparable to the processes used for forming our analogousdifunctional or monofunctional oligomers as described in U.S. Pat. Nos.4,536,559; 5,011,905; and 5,175,234.

Such polyimide oligomers exhibit a stable shelf life in the prepregform, even at room temperature, and have acceptable handling andprocessing characteristics comparable to those of K-III or PMR-15. Theyalso likely display shear/compression/tensile properties comparable toor better than PMR-15, and improved toughness, especially whenreinforced with high modulus carbon fibers. The composites areessentially fully imidized, so they are stable, insensitive toenvironmental conditions, and nonhazardous.

We will discuss linear polyimides first and then their multidimensionalcounterparts.

a. Linear polyimides

We achieve impact resistance and toughness in aromatic polyimides byincluding "sulfone" linkages (L) between the predominant imide linkagesthat characterize the backbone. The "sulfone" linkages act as joints orswivels between the aryl groups that we use to maximize the thermalstability. Thus, we select "sulfone" diamines and "sulfone" dianhydridesas the preferred reactants in the simultaneous condensation of multiplechemically functional end caps with the diamines and dianhydrides.

Although we do not prefer imide composites that include aliphaticsegments when we use our multiple chemically functional end caps, we canmake aliphatic polyimides, particularly those which include residues ofthe dianhydride MCTC. Such aliphatic residues lower the melt temperatureand allow the use of lower temperature end caps, such as oxynadic anddimethyloxynadic (DONA). The resulting aliphatic imide oligomers cure atlower temperatures than our aromatic oligomers, which may be anadvantage in some applications. Generally we prefer fully aromaticbackbones because the goal of multiple chemically functional end caps,particularly four functional caps, is to achieve the highestthermo-oxidative stability.

Sulfone (--SO₂ --) or the other electronegative linkages (L) betweenaromatic groups provide improved toughness. Our preferred imides resistchemical stress corrosion, can be thermoformed, and are chemicallystable, especially against oxidation.

i. Diamine reactants

Preferred diamines for the synthesis of imide oligomers that include ourmultiple chemically functional end caps have the formula: ##STR29##wherein R* and R' are aromatic radicals, at least one of R* and R' beinga diaryl radical wherein the aryl rings are joined by a "sulfone"linkage (L), and t is an integer from 0 to 27 inclusive. Preferably R*is selected from the group consisting of --.O slashed.--D--.O slashed.--wherein

D is an electronegative linkage selected from --SO₂ --, --(CF₃)₂ C--, or--S-- and --.O slashed.-- is phenylene. R' is preferably selected fromthe group consisting of: --.O slashed.--, --.O slashed.--M--.Oslashed.--, or

    --.O slashed.--.O slashed.--

wherein M=--SO₂ --, --S--, --O--, --(Me)₂ C--, or --(CF₃)₂ C--.

The diamine, however, may be any of: ##STR30## wherein R₅ =--.Oslashed.--q--.O slashed.--

R₆ =phenylene, biphenylene, naphthylene, or --.O slashed.--M--.Oslashed.--

q=--SO₂ --, --CO--, --S--, or --(CF₃)₂ C--, and preferably --SO₂ -- or--CO--;

m=an integer, generally less than 5, and preferably 0 or 1; and

the other variables are as previously defined.

U.S. Pat. Nos. 4,504,632; 4,058,505; 4,576,857; 4,251,417; and 4,251,418describe other diamines that we can use. We prefer the aryl or polyarylether "sulfone" diamines previously described, since these diaminesprovide high thermal stability to the resulting oligomers andcomposites. We can use mixtures of diamines, but we generally use asingle diamine in each backbone so that the resulting oligomers havereliably recurrent, predictable structure.

Our most preferred diamines are ODA, thiodianiline,3,3'-phenoxyphenylsulfone diamine; 4,4'-phenoxphenylsulfone diamine;4,4'-diaminodiphenylsulfone; 4,4'-diaminodiphenyl ether, and methylenediamine, or mixtures thereof. We often use a 50:50 molar mixture of3,3'-phenoxyphenylsulfonediamine and 4,4'-diaminodiphenylsulfone(available from Ciba-Geigy Corp. under the trade designation "Eporal").Higher temperature oligomers within the class of preferred oligomers canbe prepared using the shorter chain diamines, particularly4,4'-diaminodiphenylsulfone. The best results may be achievable byreplacing the sulfone linkage --SO₂ -- with a smaller linkage such as--O--, --S--, or --CH₂ --.

The diamines often contain one or more phenoxyphenylsulfone groups, suchas: ##STR31##

The molecular weights of the preferred aryl diamines described abovevary from approximately 500-10,000. We prefer lower molecular weightdiamines, because they are more readily available.

When the diamine has the formula (XI), the MW of these diamines varyfrom approximately 500 to about 2000. Using lower molecular weightdiamines enhances the mechanical properties of the polyimide oligomers,each of which preferably has alternating ether "sulfone" segments in thebackbones as indicated above. A typical oligomer will include up toabout 20 to 40 diamine residues, and, generally, about 5.

We can prepare phenoxyphenyl sulfone diamines useful in this imidesynthesis by reacting two moles of aminophenol with (n+1) moles of anaryl radical having terminal, reactive halide functional groups(dihalogens), such as 4,4'-dichlorodiphenyl sulfone, and n moles of asuitable bisphenol (also known as dihydroxy aryl compounds or diols).The bisphenol is preferably selected from the group consisting of:

2,2-bis-(4-hydroxyphenyl)-propane (i.e., bisphenol-A);

bis-(2-hydroxyphenyl)-methane;

bis-(4-hydroxyphenyl)-methane;

1,1-bis-(4-hydroxyphenyl)-ethane;

1,2-bis-(4-hydroxyphenyl)-ethane;

1,1-bis-(3-chloro-4-hydroxyphenyl)-ethane;

1,1-bis-(3,5-dimethyl-4-hydroxyphenyl)-ethane;

2,2-bis-(3-phenyl-4-hydroxyphenyl)-propane;

2,2-bis-(4-hydroxynaphthyl)-propane

2,2-bis-(4-hydroxyphenyl)-pentane;

2,2-bis-(4-hydroxyphenyl)-hexane;

bis-(4-hydroxyphenyl)-phenylmethane;

bis-(4-hydroxyphenyl)-cyclohexylmethane;

1,2-bis-(4-hydroxyphenyl)-1,2-bis-(phenyl)-ethane;

2,2-bis-(4-hydroxyphenyl)-1-phenylpropane;

bis-(3-nitro-4-hydrophenyl)-methane;

bis-(4-hydroxy-2,6-dimethyl-3-methoxyphenyl)-methane;

2,2-bis-(3,5-dichloro-4-hydroxyphenyl)-propane;

2,2-bis-(3-bromo-4-hydroxyphenyl )-propane;

or mixtures thereof, as disclosed in U.S. Pat. No. 3,262,914. Again,bisphenols having aromatic character (i.e., absence of aliphaticsegments), such as bisphenol A, are preferred. Other suitable bisphenols(which we also call "diols") include: ##STR32##

The bisphenol may also be selected from the those described in U.S. Pat.Nos. 4,584,364; 4,661,604; 3,262,914; or 4,611,048.

The dihalogens preferably are selected from the group consisting of:##STR33## wherein X=halogen, preferably chlorine; and L=--S--, --SO₂ --,--CO--, --(Me)₂ C--, and --(CF₃)₂ C--, and preferably --SO₂ -- or--CO--.

The condensation reaction for forming these phenoxyphenyl sulfonediamines creates diamine ethers that ordinarily include intermediate"sulfone" linkages. The condensation generally occurs through a phenatemechanism in the presence of K₂ CO₃ or another base in a DMSO/toluenesolvent. The grain size of the K₂ CO₃ (s) should fall within the 100-250ANSI mesh range.

ii. Dianhydride reactants

The dianhydride usually is an aromatic dianhydride selected from thegroup consisting of:

(a) pyromellitic dianhydride,

(b) benzophenonetetracarboxylic dianhydride (BTDA),

(c) para- and meta-dianhydrides of the general formula: ##STR34## butmay be any aromatic or aliphatic dianhydride, such as5-(2,5-diketotetrahydrofuryl)-3-methyl-cyclohexene-1,2-dicarboxylicanhydride (MCTC) or those disclosed in U.S. Pat. Nos. 4,504,632;4,577,034; 4,197,397; 4,251,417; 4,251,418; or 4,251,420. We can preparedianhydrides by condensing 2 moles of an acid halide anhydride (e.g.,trimellitic anhydride acid chloride) of the formula: ##STR35## whereinR₂ is a C.sub.(6-13) trivalent aromatic radical (typically phenylene)with a diamine selected from those previously described. We can usemixtures of dianhydrides, as we do with the EPORAL diamines. We prefer aphenoxyphenyl sulfone dianhydride of the formula: ##STR36## particularlywhen the diamine is: ##STR37## where L is previously defined.

We cure the imide oligomers or prepregs (or those counterparts for theother backbone systems) to form composites in conventional vacuum bagtechniques. We also often post-cure these imides (or any multiplechemically functional oligomer) as described in U.S. Pat. No. 5,116,935to ensure that crosslinking is substantially complete. We can use theimide oligomers (like the counterparts we describe for the other resinsbackbones) as adhesives, varnishes, films, or coatings.

b. Multidimensional polyimides

We can prepare polyimides having multidimensional morphology bycondensing the diamines, dianhydrides, and end cap monomers with asuitable amine hub, such as triaminobenzene. For example, we can reacttriaminobenzene with the phenoxyphenyl sulfone dianhydride, aphenoxyphenyl sulfone diamine, and either the extended anhydride end capmonomer or an extended amine end cap monomer to produce amultidimensional, crosslinkable polyimide. The resultingmultidimensional oligomers should have surprisingly high thermalstabilities upon curing because of the multiple chemically functionalend caps.

i. Multidimensional amine hubs

Suitable hubs include aromatic compounds having at least three aminefunctionalities. Such hubs include phenylene, naphthlylene, biphenylene,or azaline amines, (including melamine radicals) or triazine derivativesdescribed in U.S. Pat. No. 4,574,154 of the general formula: ##STR38##wherein R₁₄ is a divalent hydrocarbon residue containing 1-12 carbonatoms (and, preferably, ethylene). We use "azalinyl" or "azaline" tomean triazines represented by the formula: ##STR39##

We can form another class of amine hubs by reacting the correspondinghalo-hub (such as tribromobenzene) with aminophenol to form triaminecompounds represented by the formula: .O slashed..brket open-st.O--.Oslashed.--NH₂ !₃. We can react these triamine hubs with an anhydride endcap monomer or with suitable dianhydrides, diamines, and an extendedanhydride or an amine end cap monomer. We could also use trimelliticanhydride as a reactant in some syntheses.

Another class of suitable amine hubs comprises amines having extendedarms. For example, we can react phloroglucinol with p-amninophenol and4,4'-dibromodiphenylsulfone under an inert atmosphere at an elevatedtemperature to achieve an amino terminated "star" hub of the generalformula: ##STR40##

ii. Multidimensional anhydride hubs

In a manner analogous to the extended anhydride end cap monomers, we canprepare additional hubs for these multidimensional polyimides byreacting the corresponding hydroxy-substituted hub (such asphloroglucinol) with nitrophthalic anhydride to form trianhydride hubsrepresented by the formula: ##STR41## We can react the trianhydride witha diamine and the extended anhydride end cap monomer. Of course, we cancondense the extended anhydride end cap monomer directly with an aminehub to prepare a multidimensional polyimide oligomer or can condense theextended amine end cap monomers directly with the trianhydride.

Similarly, the hub can be an amine or anhydride derivative made from thepolyols of U.S. Pat. No. 4,709,008 that we will describe in greaterdetail later in this specification.

We present the following examples to better illustrate various featuresof the present invention as it relates to imides.

EXAMPLE 1

Synthesis of a phenoxyphenylsulfone diamine: ##STR42## wherein m has anaverage value greater than 1. (MW 5000)

In a flask fitted with a stirrer, thermometer, Barrett trap condenser,and a nitrogen inlet tube, we mix 8.04 g (0.074 moles) p-aminophenol,86.97 g (0.38 moles) bisphenol-A, 281.22 g dimethylsulfoxide (DMSO), and167.40 g toluene and stir. After purging with dry nitrogen, add 67.20 gof a 50% solution of sodium hydroxide and raise the temperature to110°-120° C. Remove the water from the toluene azeotrope, and then thetoluene, until the temperature reaches 160° C. Cool the reaction mixtureto 110° C., and add 120 g (0.42 moles) 4,4' dichlorodiphenylsulfone as asolid. Reheat the mixture to 160° C. and hold for 2 hours. After coolingto room temperature, filter the mixture to remove sodium chloride, whichprecipitates, and coagulate the product in a blender from a 2% sodiumhydroxide solution containing 1% sodium sulfite. Recover the oligomerfrom the solution by washing the coagulate with 1% sodium sulfite.

U.S. Pat. Nos. 3,839,287 and 3,988,374 disclose other methods forpreparing phenoxyphenylsulfone diamines of this general type.

EXAMPLE 2

Proposed synthesis of four functional polyimide oligomers using thediamine of Example 1, nadic-capped extended anhydride end cap monomers,and BTDA.

Charge a reaction flask fitted with a stirrer, condenser, thermometer,and a dry N₂ purge with a 60% slurry of the diamine of Example 1 in NMP.In an ice bath, gradually add a 10% solution of BDTA and an anhydrideend cap monomer in NMP. After stirring for 15 min. in the ice bath,remove the bath and stir for 2 hr. Recover the oligomer by precipitatingin water and drying with alcohol (i.e., MeOH).

Adjust the formula weight of the oligomer by adjusting the proportionsof reactants and the reaction scheme, as will be known to those ofordinary skill in the art.

EXAMPLE 3

Synthesis of the diamine: ##STR43## (MW 2,000)

Fit a reaction flask with a stirrer, thermometer, Barrett trapcondenser, and N₂ inlet tube and charged 10.91 g (0.1 moles) ofp-aminophenol, 40.43 g (0.18 moles) bisphenol A, 168.6 g DMSO, and 79.23g toluene. After purging with nitrogen, add 36.42 g of a 50% solution ofsodium hydroxide and raise the temperature to 110°-120° C. to remove thewater from the toluene azeotrope, and then the toluene until thetemperature reaches 160° C. Cool the reaction mixture to 110° C., andadd 65.22 g (0.23 moles) 4,4' dichlorodiphenylsulfone as a solid. Heatthe mixture to 160° C. and hold for 2 hours. After cooling to roomtemperature, filter the mixture to remove sodium chloride. Form acoagulate in a blender by adding 2% sodium hydroxide solution containing1% sodium sulfite. Remove the coagulate and wash it with 1% sodiumsulfite.

EXAMPLE 4

Proposed synthesis of polyimide oligomers using the diamine of Example3, a nadic extended anhydride end cap monomer, and BTDA.

Use the procedure followed in Example 2, except substitute a suitableamount of the diamine of Example 3 for the diamine of Example 1.

EXAMPLE 5

Synthesis of a diamine of Example 1 (MW 10,000).

Use the procedure of Example 1, using 2.18 g (0.02 moles) ofp-aminophenol, 49.36 g (0.216 moles) of bisphenol-A, and 64.96 g (0.226moles) of 4,4'-dichlorodiphenyl-sulfone.

EXAMPLE 6

Proposed synthesis of four functional polyimide oligomers using thediamine of Example 5, the extended anhydride end cap monomer, andphenoxyphenylsulfone dianhydride.

Follow the procedure in Example 2, substituting the diamine of Example5, the extended anhydride end cap monomer, and phenoxyphenylsulfonedianhydride as the reactants.

EXAMPLE 7

Proposed preparation of composites from four functional linearpolyimides.

The oligomers obtained in any of Examples 2, 4, and 6 can be impregnatedon epoxy-sized T300/graphite fabric style (Union Carbide 35 millionmodulus fiber 24×24 weave) by first obtaining a 10 to 40% solution ofresin in NMP or another appropriate aprotic solvent, including DMAC orDMF. The solutions can then be coated onto the dry graphite fabric toform prepregs with 38 wt. % resin. The prepregs can be dried to lessthan 1 percent volatile content, cut into 6×6-inch pieces, and stackedto obtain a consolidated composite of approximately 0.080 inch. Thestacks of prepregs can then be vacuum bagged and consolidated under100-200 psi in an autoclave heated for a sufficient time probably for1-2 hours at 575°-600° F. (300°-315° C.)! to induce cure. If dimethyloxynadic or oxynadic anhydride capped systems are used, the prepregslikely would be cured for 16 hours at 400° F. (210° C.).

EXAMPLE 8

Proposed preparation of polyimide composites for oligomers having fourfunctional caps.

Prepare graphite fabric prepregs, at 36 percent resin solids, using theresins of Example 2, 4, and 6 by solvent impregnation from a dilute NMPor another aprotic solvent solution. The graphite fabric is spread on arelease film of FEP. Sweep the prepregging solution (havingapproximately 10-40 wt. % oligomer) into the fabric and allow it to dry,repeating on alternating sides, until the desired weight of resin isapplied. The prepregs can then be dried 2 hours at 275° F. (135° C.) inan air-circulating oven.

Stack seven piles of each prepreg, double-wrapped in release-coated2-mil Kapton film, and sealed in a vacuum bag for curing. Place eachvacuum bag assembly in an autoclave and heat to about 575°-600° F.(300°-315° C.) at a rate of 1°-2° F./min. (0.5°-1° C./min.). Uponreaching 575°-600° F. (300°-315° C.), hold the temperature substantiallyconstant for about 2 hr to complete the cure. To enhance hightemperature properties, post-cure for about 4-8 hr at 600°-625° F.(315°-330° C.).

EXAMPLE 9

Anticipated solvent resistance of four functional polyimide composites.

Samples of the cured composites of Example 8 can be machined into1×0.5-inch coupons, placed in bottles containing methylene chloride, andobserved to determine if ply separation occurs. The composites willlikely remain intact, with only slight swelling, after immersion for upto 2 months.

c. Post-curing

In another aspect of the invention, we can improve the thermal stabilityof the imide composites by post-curing the composites at temperatures ofup to approximately 625°-650° F. (315°-330° C.). Post-curing isdesirable for all resin types. It promotes complete linking. Suchpost-curing treatment advantageously raises the dynamic mechanicalanalysis peak (and β-transition) of the treated composites, presumablyby causing full crosslinking of the end cap functionalities. Preferably,we carry out the post-curing treatment of the composites at atemperature of about 625°-650° F. (315°-330° C.) for a period ofapproximately 2-4 hours, but this period may vary somewhat dependingupon the particular composite being treated.

The thermal stabilities achievable with such post-curing treatment aresignificantly higher than those generally realized without thetreatment. For example, for a difunctional polyimide oligomer having aMW of about 15,000 and prepared as previously described by reacting adifunctional imidoaniline end cap, 4,4'-phenoxyphenylsulfonedianhydride, and a 50:50 molar mixture of 3,3'-phenoxyphenylsulfonediamine and 4,4'-diaminodiphenylsulfone, post-curing at a temperature ofapproximately 625°-650° F. (315°-330° C.) resulted in a DMA transitiontemperature of about 350° F. (177° C.), some 40°-50° F. (20°-25° C.)higher than without such treatment. We believe there will be acomparable benefit from post-curing four functional oligomers of thepresent invention.

In carrying out the post-cure treatment, a prepreg is first formed byimpregnating a fabric with a polyimide oligomer. The fabric can be anyof the types previously described. We heat the prepreg at an elevatedtemperature (e.g. 450° F. (232° C.)) and under pressure (e.g. 100 psi)for a time sufficient to cure the prepreg and form a composite. We thenpost-cure the resulting composite at a temperature of approximately625°-650° F. (315°-330° C.) for a time sufficient to improve the thermalstability. During post-curing, the remaining unreacted crosslinkingfunctionalities re-orient and react to produce a nearly fully linkedchain.

Post-curing applies to all the resin backbones. It ensures more completereaction of the capping functionalities. We recommend it for all ourmultifunctional oligomer systems.

The bisphenol may be in phenate form, or a corresponding sulfhydryl canbe used. Of course, can use we mixtures of bisphenols and bisulfhydryls.

Bisphenols of the type described are commercially available. Some may beeasily synthesized by reacting a dihalogen intermediate withbis-phenates, such as the reaction of 4,4'-dichlorophenylsulfone withbis(disodium biphenolate). Preferred dihalogens in this circumstance arethose we discussed for forming diamines.

d. Multidimensional acid hubs

While acid hubs are not used in the imides, we describe them here whilediscussing extended hubs. We can convert the triazine derivativesdescribed in U.S. Pat. No. 4,574,154 to acid halides by reacting theamine functionalities with phthalic acid anhydride to form imidelinkages and terminal acid functionalities (that we convert to acidhalides). We can also use the triazine derivatives of U.S. Pat. No.4,617,390 (or the acid halides) as the hub for multidimensionalheterocycles.

By reacting polyol aromatic hubs, such as phloroglucinol, withnitrobenzoic acid or nitrophthalic acid to form ether linkages andterminal carboxylic acid functionalities, we produce acid hubs. Thenitrobenzoic acid products would have three active sites while thenitrophthalic acid products would have six; each having the respectiveformula: ##STR44## Of course we can use other nitro/acids.

We can react extended triamine hubs of the formula: ##STR45## with anacid anhydride (i.e., trimellitic acid anhydride) to form apolycarboxylic acid hub of the formula: ##STR46## the hub beingcharacterized by an intermediate ether and imide linkage connectingaromatic groups. We can also use thio-analogs in accordance with U.S.Pat. No. 3,933,862.

4. Amideimide Oligomers

Polyamideimides are generally injection-moldable, amorphous, engineeringthermoplastics which absorb water (swell) when subjected to humidenvironments or immersed in water. Typically Polyamideimides aredescribed in the following patents: U.S. Pat. No. 3,658,938; U.S. Pat.Nos. 4,628,079; 4,599,383; 4,574,144; or 3,988,344. Theirthermomechanical integrity and solvent-resistance can be greatlyenhanced by capping amideimide backbones with the four functional endcap monomers.

Classical amideimides have the characteristic repeating unit: ##STR47##in the backbone, usually obtained by reacting equimolar amounts oftrimellitic acid halide anhydride and a diamine to form a polymer of theformula: ##STR48## wherein R* is the residue of the diamine and mrepresents the polymerization factor. While we can make amideimides ofthis type, and quench them to oligomers by using an extended amine endcap monomer mixed with the diamine and trimellitic acid halide anhydride(see Example 38), we also make more varied amideimide oligomers.

Our oligomers can also be four functional capped homologs of the TORLONamideimides.

a. Linear amideimides

The amideimdes of the present invention generally include linkages ofthe following general nature along the backbone: ##STR49## wherein

R₈ =an aromatic, aliphatic, or alicyclic radical, and preferably aphenoxyphenyl sulfone; and

R₁₁ =a trivalent organic radical, typically a C.sub.(6-13) aromaticradical such as phenylene.

R₈ is the residue of a diamine and, throughout the amidemide chain, canbe the same or different depending on whether we use a single diamine ora mixture of diamines. We prepare random or block copolymers. We canprepare an amide-amide-imide-imide linkage, for example, by condensing 2moles of an acid halide anhydride (e.g., trimellitic anhydride acidhalide) of the general formula: ##STR50## with a diamine of the formula:H₂ N--R₈ --NH₂ to produce an intermediate dianhydride. The linkage ischaracterized by a plane of symmetry about the R₈ residue. We can useany of the diamines described for the imides.

R₁₁ is commonly phenylene, so that the products are classicalamideimides.

We can prepare the corresponding amideimide of the general formula:##STR51## if we use the acid anhydride (e.g., trimellitic acidanhydride): ##STR52## instead of the acid halide anhydride (e.g.,trimellitic anhydride acid halide), because the imide forms before theamide. This reaction proceeds through a dicarboxylic acid intermediate.

We can also prepare true amideimides as our U.S. Pat. No. 5,155,206describes. In the present invention we condense an appropriate fourfunctional end cap monomer with the reactants in place of theimidoaniline or acid halide caps used in our earlier patents.

We can synthesize true amideimides of the present invention by severalschemes. To obtain repeating units of the general formula: ##STR53## wemix an acid halide anhydride, particularly trimellitic anhydride acidchloride: ##STR54## with a diamine from those described for the imidesand with an extended amine end cap in the ratio of n: n: 2 wherein n=aninteger. The acid halide anhydride reacts with the diamine to form anintermediate dianhydride which will condense with the remaining diamineand the amine end cap monomer. The reaction may be carried out in twodistinct stages under which the dianhydride is first prepared by mixingsubstantially equimolar amounts (or excess diamine) of the acid halideanhydride and diamine followed by the addition of a mixture of thediamine and the end cap monomer. Of course, the diamine used to form thedianhydride may differ from that used in the second stage of thereaction, or there can be a mixture of diamines from the outset.

We can synthesize the related amideimide having repeating units of thegeneral formula: ##STR55## by reacting the acid anhydride with thediamine to form an intermediate dicarboxylic acid, which can then reactwith more diamine, another diamine, or an amine end cap monomer tocomplete the oligomer. Again, the reaction can be divided into steps.

The amideimide oligomers will probably improved if the condensation ofthe dianhydride/dicarboxylic acid with the diamine and end cap monomeris done simultaneously rather than sequentially.

While the oligomers we describe use an amine end cap, we can synthesizecorresponding oligomers by using an acid halide end cap or even ananhydride end cap, if the diamine is provided in excess. The reactionmixture generally comprises the anhydride acid halide (--COX) or theacid anhydride (--COOH), the end cap monomer, and the diamine with thesynthesis completed in one step.

All reactions should be conducted under an inert atmosphere. Reducingthe temperature of the reaction mixture, such as by using an ice bath,can slow the reaction rate and can assist in controlling the oligomericproduct.

As suggested in U.S. Pat. No. 4,599,383, the diamine may be in the formof its derivative OCN--R--NCO, if desired.

We can multifunctionally cap any amideimide described in U.S. Pat. Nos.4,599,383; 3,988,374; 4,628,079; 3,658,938; and 4,574,144 with anappropriate crosslinking end cap monomer, such as the acid halide endcap, to convert the polymers to four functional oligomers of the presentinvention.

We can use a sequential or homogeneous reaction scheme to condense thereactants with sequential synthesis preferred to avoid side reactions.Generally we condense a dianhydride or diacid halide (depending onwhether the acid halide anhydride or simply the acid anhydride is used)diamine, and an extended anhydride end cap monomer of formula (II). Thatis, we can prepare the dianhydride or diacid halide by the condensationof a diamine with the acid anhydride or acid halide anhydride followedby addition of additional diamine and the end cap to complete thesynthesis. Four functional analogs of the amideimides described in ourU.S. Pat. Nos. 5,104,967; 5,155,206; 5,216,117; and 5,239,046 can beprepared.

b. Multidimensional amideimides

The multidimensional polyamideimide oligomers include oligomers of thegeneral formula: ##STR56## and other four functional, multidimensionalamideimide oligomers analogous to the monofunctional and difunctionalmultidimensional amideimide oligomers our U.S. Pat. Nos. 5,227,461;5,104,967; or 5,155,206 describe.

Diacid halide reactants

The diacid halide (or dicarboxylic acid i.e., dibasic acid!; generalformula: XOC--R₉ --COX) may include an aromatic chain segment (i.e., R₉)selected from the group consisting of:

(a) phenylene;

(b) naphthylene;

(c) biphenylene;

(d) a polyaryl "sulfone" divalent radical of the general formula:

    --.O slashed.--O--.O slashed.--L*--.O slashed.--O--.O slashed.--

wherein L*=--S--, --O--, --CO--, --SO₂ --, --(Me₃)₂ C--, or --(CF₃)₂C--,

(e) a divalent radical having conductive linkages, illustrated by Schiffbase compounds, selected from the group consisting of: ##STR57## whereinR is selected from the group consisting of: phenylene; biphenylene;naphthylene; or a divalent radical of the general formula: --.Oslashed.--W--.O slashed.-- wherein W=--SO₂ -- or --CH₂ --; and g=0-4; or

(f) a divalent radical of the general formula:

    --R.sub.10 --NHCO--.O slashed.--CONH--

wherein R₁₀ =a C₂ to C₁₂ divalent aliphatic, alicyclic, or aromaticradical, and, preferably, phenylene (as described in U.S. Pat. No.4,556,697).

The preferred diacid halide is a dibasic carboxylic acid halide of adivalent organic radical selected from the group consisting of:##STR58## wherein m is an integer, generally from 1-5, and the othervariables are as previously defined.

The most preferred acid halides include: ##STR59##

We can prepare Schiff base diacid halides by the condensation ofaldehydes and aminobenzoic acid halide (or other amine/acids) in thegeneral reaction scheme: ##STR60## or similar syntheses.

U.S. Pat. No. 4,504,632, discloses other diacid halides that we can useincluding:

adipylchloride,

malonyl chloride,

succinyl chloride,

glutaryl chloride,

pimelic acid dichloride,

suberic acid dichloride,

azelaic acid dichloride,

sebacic acid dichloride,

dodecandioic acid dichloride,

phthaloyl chloride,

isophthaloyl chloride,

terephthaloyl chloride,

1,4-naphthalene dicarboxylic acid dichloride, and

4,4'-diphenylether dicarboxylic acid dichloride.

We prefer polyaryl or aryl diacid halides to achieve the highest thermalstabilities in the resulting oligomers and composites. Particularlypreferred compounds include intermediate "sulfone" (i.e.electronegative) linkages (i.e., "L") to improve the toughness of theresulting oligomers.

Suitable diacid halides include compounds made by reacting nitrobenzoicacid with a bisphenol (which might also be called a dihydric phenol,dialcohol, or diol). The reaction is the counterpart of that for makingdiamines. The bisphenol is preferably selected from the group previouslydescribed for the imide syntheses. We prefer bisphenols having aromaticcharacter (i.e., absence of aliphatic segments), such as bisphenol-A.While we prefer bisphenol-A (because of cost and availability), we canuse the other bisphenols to add rigidity to the oligomer withoutsignificantly increasing the average formula weight over bisphenol-Aresidues, and, therefore, can increase the solvent resistance. Random orblock copolymers from using different bisphenols are possible (here aswell as with the other backbones).

c. Amideimide sizings

A major problem encountered in improving high temperature mechanical andphysical properties of reinforced resin composites occurs because ofinadequate transfer of induced matrix stress to the reinforcement. Thematrix also helps to prevent the fiber from buckling. Sizing is oftenapplied to the reinforcing fibers to protect the fibers duringprocessing and to enhance bonding at this interface between the fibersand the resin matrix thereby more efficiently transferring the load andstabilizing the fiber. Sizings are essentially very thin films of resin(less than a few wt %) applied to the fibers. To be effective, sizingsshould be relatively high MW materials that form a relatively uniformcoating. Commercially available sizings include epoxy sizings under thetrade designations UC309 and UC314 from Amoco, G or W from Hercules,EP03 front Hoechst and high performance sizings under the tradedesignations L30N, L20N, UC0121 or UC0018 from Amoco. Commerciallyavailable sizings are unsatisfactory because they are generally monomersor low MW materials that often only partially coat the fibers and, as aresult, minimally improve composite properties. There is a need,therefore, for improved sizings, especially for carbon fibers intendedfor high performance composites.

We described improved sizings for carbon fibers using an amideimidepolymer or a difunctional amideimide oligomer in our U.S. Pat. Nos.5,155,206 and 5,239,046. We can now prepare analogous four functionalamideimide sizings, although they likely would provide littleimprovement over polymeric amideimide sizings since capping between thematrix and sizing would be disorganized and incomplete at best. Theamideimide polymer, a difunctional oligomer, the four functionaloligomers of the present invention, or blends of any of these polymersand oligomers might be used. A four functional amideimide sizing isprobably best when using a four functional oligomer as the matrix for asizing, the amideimide should have a MW above 10,000, and, preferably,above 20,000. Actually, the MW should be as high as one can achieve. Asfor the polymers and difunctional oligomers, a preferred four functionalamideimide oligomer is formed by condensing trimellitic anhydride acidchloride with bis(4-aminophenoxyphenyl) sulfone and either an extendedamine, an acid chloride, or a phenol end cap monomer.

When the matrix is an oligomer that includes crosslinkingfunctionalities of the nature suggested for the capped sizings of thepresent invention, it is probably wise that the caps on the oligomer andon the sizings be the same or at least chemically comparable. That is,for example, we prefer to use nadic caps in our oligomers and nadic capsfor the amideimide sizing.

We believe that the amideimide sizings provide a high concentration ofhydrogen bonding sites to promote coupling between the sizing and thematrix. Both the imide and amide linkages include heteroatoms. Thecapped materials may actually form chemical (covalent) bonds for evenstronger interaction between the sizing and matrix, or the end capsmight cause addition polymerization to provide even higher MW sizings onthe fiber. We believe higher MW sizings have better properties.

The sizings impart improved elevated temperature mechanical andenvironmental stability to carbon fiber/oligomer composites in which thematrix resin is selected from imides, amides, amideimides, esters,ethers, sulfones, ether sulfones, heterocycles, carbonates, and almostany other commercial resin including epoxies, PMR-15, K-III, or thelike. We use these multifunctional amideimide sizings in the same manneras conventional sizings.

We next provide some examples of proposed syntheses of polyamideimides.

EXAMPLE 10

React a diamine with two moles of trimellitic acid anhydride to form adicarboxylic acid intermediate by adding the diamine dropwise to thetrimellitic acid anhydride. Convert the intermediate to thecorresponding diacid chloride in the presence of SOCl₂, and thencondense the intermediate with the diamine and an extended amine end capmonomer to yield the desired product.

If excess diamine is used, use an acid halide end cap to form theproduct.

EXAMPLE 11

React a diamine with trimellitic anhydride acid chloride to yield adianhydride intermediate. Condense the intermediate with an amine endcap monomer and a diamine to yield the desired product.

Typically, this reaction involves mixing, for example, the fournadic-capped acid chloride end cap monomer: ##STR61## wherein NA isnadic and .O slashed. is phenylene with trimellitic acid chlorideanhydride: ##STR62## in NMP or another suitable solvent and, then,adding the diamine:

    H.sub.2 N--.O slashed.--O--.O slashed.--SO.sub.2 --.O slashed.--O--.O slashed.--NH.sub.2

in NMP (i.e., the same solvent). We prepare the diamine by reactingpara- or meta-aminophenol with ##STR63##

It may be possible to obtain the amideimide in another fashion,involving protecting the amine functionalities in the cap thatultimately form the amide linkages with phthalic anhydride; condensingthe protected phthalic imide acid chloride end cap monomer the diamine,and trimellitic acid chloride anhydride; saponifying the resultingproduct to yield a bis(diamino) oligomer; and completing the capping bycondensing a phthalimide acid halide end cap monomer, such as those inU.S. Pat. No. 5,087,701, and, preferably the dinadic acid chloridemonomer. Our concern with this scheme is whether the sapionificationreaction will also break the imide linkages in the backbone.

EXAMPLE 12

Condense triaminobenzene with a trimellitic acid anhydride or acidchloride and an amine end cap monomer to yield the desiredmultidimensional product. Any amine hub can be used in place oftriaminobenzene.

EXAMPLE 13

React an amine hub with the dicarboxylic acid intermediate of Example15, a diamine, and an extended amine end cap in the ratio of 1 mole ofhub: (w)(m+1) moles of intermediate:(w)(m) moles of diamine: w moles ofend cap to prepare the desired multidimensional product.

EXAMPLE 14

React an amine hub with the dianhydride intermediate of Example 11, adiamine, and the extended amine end cap in the ratio of 1 mole hub:(w)(m+1) moles dianhydride: (w)(m) moles diamine: w moles end cap toyield the desired product.

EXAMPLE 15

React an acid or acid halide hub, like cyuranic acid, with a diamine, adicarboxylic acid intermediate of Example 10, and an acid halide end capin the ratio of 1 mole hub: (w)(m+1) moles diamine: (w)(m) molesintermediate: w moles cap to yield the desired product.

EXAMPLE 16

React an amine hub with a dicarboxylic acid intermediate (or dihalide)of Example 10 and the extended amine end cap in the ratio of 1 mole hub:w moles intermediate: w moles cap to yield the desired product.

EXAMPLE 17

React an amine hub with the dicarboxylic acid intermediate of Example10, a diamine, and an acid halide end cap in the ratio of 1 mole hub: wmoles intermediate: w moles diamine, and w moles cap to form the desiredproduct.

EXAMPLE 18

React an amine hub with the dianhydride intermediate of Example 10, adiamine, and an acid halide end cap in the ratio of 1 mole hub: (w)(m)moles intermediate: (w)(m) moles diamine: w moles cap to form thedesired product.

EXAMPLE 19

React an amine hub with the dicarboxylic acid intermediate of Example10, a diamine, and an extended amine end cap in the ratio of 1 mole hub:(w)(m+1) moles intermediate: (w)(m) moles diamine: w moles cap to formthe desired product.

EXAMPLE 20

React an amine hub with trimellitic anhydride acid halide, a diamine,and an acid halide end cap in the ratio of 1 mole hub: with molestrimellitic anhydride acid halide: w moles diamine: w moles cap to formthe desired product. Preferably the reaction occurs in two steps withthe reaction of the hub and trimellitic anhydride acid halide followedby the addition of an amine end cap.

EXAMPLE 21

React an amine hub with trimellitic acid anhydride and an extended amineend cap in the ratio of 1 mole hub: w moles trimellitic acid anhydride:w moles cap to form the desired product.

EXAMPLE 22

React an amine hub with trimellitic acid anhydride, a diamine, and anextended amine end cap in the ratio of 1 mole hub: 2w moles acidanhydride: w moles diamine: w moles cap to yield the desired product.Preferably the cap and half of the acid anhydride are mixed to form anend cap conjugate prior to mixing the reactants to form the oligomer. Italso may be wise to mix the remaining acid anhydride with the hub toform an acid hub conjugate prior to adding the diamine and end capconjugate. In an alternate synthesis we use an anhydride end capmonomer.

Alternatively, make the product by reacting the hub with the dianhydrideintermediate of Example 11 and an extended amine end cap.

EXAMPLE 23

React an amine hub with the dianhydride intermediate of Example 11, adiamine, and either an extended anhydride end cap conjugate formed byreacting an amine end cap with an acid halide anhydride (liketrimellitic acid chloride anhydride) or the anhydride end cap monomer inthe ratio of 1 mole hub: w moles intermediate: w moles end capconjugate.

Alternatively, prepare the product by reacting the hub with an acidanhydride followed by reaction with a diamine, the diacid intermediateof Example 10, and an amine end cap. Stepwise addition of the diamine tothe extended hub followed by addition of the diacid intermediate andamine end cap will reduce competitive side reactions.

EXAMPLE 24

React an amine hub with an acid anhydride (like trimellitic acidanhydride) to form an acid hub intermediate. React the intermediate witha diamine, a dicarboxylic acid or acid halide intermediate of Example10, and an acid halide end cap in the ratio of 1 mole hub intermediate:(w)(m+1) moles diamine: (w)(m) moles dicarboxylic acid intermediate: wmoles end cap to yield the desired product.

Alternatively, prepare the product by reacting an amine hub with thedianhydride intermediate of Example 11, a first diamine, an acidanhydride, a second diamine, and an acid halide end cap in a stepwisereaction.

EXAMPLE 25

React an amine hub with the dianhydride intermediate of Example 11, adiamine, and an extended amine end cap in the ratio of 1 mole hub: 2wmoles intermediate: w moles diamine: w moles cap to yield the desiredproduct.

EXAMPLE 26

React an acid hub with a diamine, an acid anhydride, and an amine endcap in the ratio of 1 mole hub: w moles diamine: w moles acid anhydride:w moles cap to yield the desired product. Preferably the reactionincludes the steps of reacting the acid anhydride with the end capmonomer prior to addition of the hub and diamine.

EXAMPLE 27

React an acid hub with a diamine to form an amine extended hubconjugate. React the conjugate with an acid halide anhydride, a seconddiamine, and an acid halide end cap to yield the desired product.Preparing an end cap conjugate by reacting the second diamine with theacid halide cap (adding the cap dropwise to the diamine) prior to theaddition of the other reactants reduces side or competitive reactions.In this case, for example, the acid hub is added dropwise to the diamineto promote substantially complete addition of the free amino groups withthe hub's acid functionalities and to minimize addition of a hub to bothends of the diamine. We take similar precautions in making the otherconjugates we describe in these examples.

EXAMPLE 28

React an acid hub with a diamine, the acid intermediate of Example 10,and an extended amine end cap in the ratio of 1 mole hub: w molesdiamine: w moles intermediate: w moles cap. Preferably, the reactionoccurs in two stages with the hub being mixed with the diamine to forman amine conjugate to which the acid or acid halide intermediate and capis added in a simultaneous condensation.

EXAMPLE 29

React an acid hub with a diamine, the acid intermediate of Example 10,and an extended amine cap in the ratio of 1 mole hub: (w)(m+1) molesdiamine: (w)(m) moles intermediate: w moles cap to yield the desireproduct. The reaction preferably involves the step of preparing theamine conjugate described in Example 33.

EXAMPLE 30

React two moles of an extended amine end cap with about (m+2) moles oftrimellitic acid anhydride, and about (2m+1) moles of bis(4-aminophenoxyphenyl)sulfone:

    H.sub.2 N--.O slashed.--SO.sub.2 --.O slashed.--O--.O slashed.--SO.sub.2 --.O slashed.--NH.sub.2,

to yield the desired product. To avoid side or competitive reactions,prepare a dicarboxylic acid intermediate by mixing the acid anhydrideand diamine in the ratio of about 2 moles acid anhydride: 1 mole diamineprior to adding the remaining reactants for simultaneous condensation tothe oligomer.

EXAMPLE 31

Follow the method of Example 10 except substitute aniline for the aminecap. The product is a comparable amideimide polymer of similar MW andstructure to the oligomer of Example 10 but being incapable ofcrosslinking because of the lack of crosslinking sites (hydrocarbonunsaturation) in the end caps. The aniline provides MW control andquenches the amideimide condensation.

We can obtain comparable noncrosslinking amideimide polymers using themethods of Examples 11-30 substituting aniline, benzoic acid, or similarcompounds to quench the syntheses, as will be understood by those ofordinary skill. In analogous manner, we can make corresponding,noncrosslinking polymers for any oligomer we describe in thisspecification, and we can use these polymers in blends.

EXAMPLE 32

Mix solutions of the amideimide oligomer of Example 10 and theamideimide polymer made in accordance with Example 31 to prepare a blendthat either can be swept out into fiber reinforcement to form a prepregof an amideimide blend or that can be dried to recover the blend. Theblend generally includes substantially equimolar amounts of the oligomerand polymer, although the ratio can be varied to control the propertiesof the blend.

EXAMPLE 33

Dissolve an extended amine end cap and bis(4-aminophenoxyphenyl) sulfonein N,N'-dimethylacetamide (DMAC). Cool the solution to -10° C. undernitrogen. While stirring, add trimellitic anhydride acid chloridedropwise and hold the temperature below 0° C. one hour. Next addtriethylamine (TEA) dropwise and stir 30 minutes. Add DMAC and stir 3more hours. Finally, add pyridine and acetic anhydride. Stir the viscousmixture 3 hours. Filter off the hydrochloride salt and precipitate theproduct in a blender with water. Filter, wash the precipitate theproduct with distilled water and then dry.

Alternatively, the imidization reaction can be induced thermally byheating the mixture to about 300°-350° F. (150°-175° C.) for severalhours followed by precipitating the product in water and washing withMeOH.

EXAMPLE 34

A proposed linear advanced composite blend.

Make an amideimide oligomer in accordance with Example 10.

Make a relative high MW polyether polymer by condensing a diol of thegeneral formula:

    HO--.O slashed.--O--.O slashed.--O--.O slashed.--O--.O slashed.--OH

with Cl--.O slashed.--Cl and phenol or chlorobenzene (to quench thepolymerization) under an inert atmosphere in the same solvent as usedwith the amideimide oligomer or another solvent miscible with that ofthe amideimide oligomer.

Mix the two solutions to form a lacquer or varnish of an advancedcomposite blend. Prepreg the lacquer or dry it prior to curing the blendto an advanced amideimide/ether composite. This advanced composite blendcould be mixed with a Z*_(k) --B--Z*_(k) oligomer to form a coreactiveoligomer blend, which would, then, be prepregged and cured. "Z*" is acyclobutane, amine, phenol, or thioether.

For additional discussion of advanced composite blends, see section 14.Section 15 discusses coreactive oligomer blends in more detail.

EXAMPLE 35

A proposed multidimensional advanced composite blend.

Prepare a multidimensional, polyether sulfone polymer by reactingphloroglucinol with Cl--.O slashed.--Cl and HO--.O slashed.--O--.Oslashed.--SO₂ --.O slashed.--O--.O slashed.--OH. Quench thepolymerization with either chlorobenzene or phenol. The condensationoccurs in a suitable solvent under an inert atmosphere. The product isnot recovered from the solvent.

Prepare a multidimensional, ester oligomer in the same solvent as usedfor the polymer or in another miscible solvent by condensing cyuranicacid chloride with a phenol end cap. The oligomer product is notrecovered, but the reaction mixture is mixed with the polyether polymerproduct and a phenoxyphenyl sulfone diamine (i.e., Z--B--Z, such asbis(4-aminophenoxyphenyl)sulfone) to form a multidimensional advancedcomposite blend of coreactive oligomers that can be prepregged or driedprior to curing the ester oligomer to form a multidimensional,polyester/polyethersulfone, advanced composite.

Generally, in coreactive oligomer blends, the resins are selected totailor the physical properties of the resulting block copolymercomposites. Such blends with multiple chemically functional oligomersare counterparts to the coreactive oligomer blends U.S. Pat. Nos.5,115,087 and 5,159,055 describe. For example, we can achieve stiffeningfor a composite made from ethersulfone oligomer of the present inventionby adding a benzoxazole oligomer as a coreactant. Those skilled in theart will recognize the benefits to be gained through coreactive oligomerblends. The ethersulfone toughens the relatively stiff and rigidheterocycle oligomers, which is particularly important for thepreparation of films.

To prepare ethers, the phenol or halide end cap is mixed with suitablediols and dihalogens or with suitable dinitrohydrocarbons and diols. Toprepare esters, the phenol end cap or acid halide end cap is mixed withsuitable diols and diacids, both as will be explained in greater detaillater in this specification.

5. Etherimides

The polyetherimides and polysulfoneimides of the present invention areanalogous to the oligomers described in U.S. Pat. Nos. 4,851,495 and4,981,922 and have the general formula: ##STR64## wherein ρ=--O-- or--S--;

ξ=the residue of an end cap;

R₁₁ =a trivalent C.sub.(6-13) aromatic organic radical;

R₁₃ =a divalent C.sub.(6-30) aromatic organic radical; and

m=a small integer (the "polymerization factor") typically from 1-5.

We prepare the polyetherimide oligomers by several reaction schemes. Onemethod for synthesizing the polyetherimides involves the simultaneouscondensation of about 2m+2 moles of nitrophthalic anhydride with aboutm+1 moles of diamine, about m moles of a diol, and the extended amineend cap or the extended phenol end cap in a suitable solvent under aninert atmosphere. The diol may actually be in the form of a phenate.

In this reaction, the diamines (which preferably have aromaticethersulfone backbones) react with the anhydride of the nitrophthalicanhydride to form dinitro intermediates and the diol reacts with thenitro-functionality to form an ether linkage as described in our U.S.Pat. Nos. 4,851,495 and 4,981,922. The end caps quench thepolymerization.

Another method comprises the simultaneous condensation of: ##STR65## inthe ratio of XII:XIII:XIV:XV=l:l:m:m, wherein ν=halo- or nitro-. Theproduct has the general formula previously described. The reactionconditions are generally comparable to those described in U.S. Pat. Nos.3,847,869 and 4,107,147.

Alternatively, we prepare the polyetherimides by reacting apolyetherimide polymer made by the self-condensation of a phthalimidesalt of the formula: ##STR66## wherein M₂ is an alkali metal ion orammonium salt or hydrogen with quenching crosslinking end cap moietiesof the formula: ##STR67## and a halogeno cap of the formula: ##STR68##wherein Z is an end cap and X is a halogen.

The self-condensation proceeds as described in U.S. Pat. No. 4,297,474in a dipolar aprotic solvent. We introduce the end cap moieties eitherduring the self-condensation to quench the polymerization or followingcompletion of the polymerization and recovery of the polyetherimidepolymer from methanol (i.e., post-polymerization capping).

Another etherimide synthesis comprises the simultaneous condensation ofabout 2m+2 moles of nitrophthalic anhydride with about m+1 moles ofdiol, m moles of diamine, and 2 moles of the extended amine end cap in asuitable solvent under an inert atmosphere.

In any of the syntheses, we can replace the diol by a comparabledisulfhydryl. We can use mixtures of diols and disulfhydryls, of course,but we prefer pure diols.

We can synthesize the oligomers in a homogeneous reaction scheme whereinall the reactants are mixed at one time (and this scheme is preferred),or in a stepwise reaction. We can mix the diamine and diols, forexample, followed by addition of the nitrophthalic anhydride to initiatethe polymerization and thereafter addition of the end caps to quench it.Those skilled in the art will recognize the different methods that mightbe used. To the extent possible, we minimize undesirable competitivereactions by controlling the reaction steps (i.e., addition ofreactants) and the reaction conditions.

Although we can use any diol (i.e., bisphenol) previously described, foretherimides, we prefer a diol selected from the those described in U.S.Pat. Nos. 4,584,364; 3,262,914; or 4,611,048 or a polyaryl diol selectedfrom the group consisting of:

HO--Ar--OH;

HO--Ar--Σ--Ar'--Σ--Ar--OH;

HO--Ar'--Σ--Ar--Σ--Ar'--OH;

wherein

Σ=--CH₂ --, --(Me)₂ C--, --(CF₃)₂ C--, --O--, --S--, --SO₂ -- or --CO--;##STR69## R₁ =lower alkyl, lower alkoxy, aryl, aryloxy, substitutedalkyl, substituted aryl, halogen, or mixtures thereof;

g=0-4;

k₁ =0-3; and

j=0, 1, or 2.

The preferred diols include hydroquinone; bisphenol-A; p,p'-biphenol;4,4'-dihydroxydiphenylsulfide; 4,4'-dihydroxydiphenylether;4,4'-dihydroxydiphenylisopropane; or4,4'-dihydroxydiphenylhexafluoropropane. We prefer to use a single diolrather than mixtures of diols. Actually, for the reactants in any of oursyntheses, we prefer to use a pure compound rather than a mixture. Weoften seek the highest purity available for the selected reactantbecause we seek to make the highest MWs we can synthesize.

We prefer bisphenol-A as the diol because of cost and availability. Theother diols can be used, however, to add rigidity to the oligomer andcan increase the solvent resistance. Random or a block copolymers arepossible by using mixed diols as the reactant, but we do not preferthem.

In the coreactive oligomer blends (Section 15), we can use these diolsas the Z*_(k) --B--Z*_(k) oligomers wherein k=1.

Suitable diamines include those diamines described with reference to theimide synthesis or elsewhere in this specification.

In at least one synthesis of the etherimides, a compound of the formula:##STR70## is an intermediate or reactant (i.e., it is a halogeno endcap). We form this intermediate by reacting the corresponding extendedamine end cap with halo- or nitrophthalic anhydrides described in U.S.Pat. Nos. 4,297,474 and 3,847,869, which also are incorporated byreference.

We synthesize multidimensional etherimides by reacting the anhydride hubwith compounds of formulae (XII) through (XV), previously described.Those skilled in the art will recognize other mechanisms to makemultidimensional etherimide oligomers based on the mechanisms weillustrated for the imides and amideimides.

Our etherimide oligomers can be four functional capped homologs of theULTEM or KAPTON etherimides that are commercially available.

6. Polysulfoneimides

We can prepare polysulfoneimide oligomers corresponding to theetherimides and analogous to those described and claimed in U.S. patentapplication Ser. No. 07/241,997 by reacting about m+1 moles of adianhydride with about m moles of a diamine and about 2 moles of anextended amine end cap. The resulting oligomer has the general formula:##STR71## wherein R and R' are divalent aromatic organic radicals havingfrom 2-20 carbon atoms. R and R' may include halogenated aromaticC.sub.(6-20) hydrocarbon derivatives; alkylene radicals andcycloalkylene radicals having from 2-20 carbon atoms; C.sub.(2-8)alkylene terminated polydiorganosiloxanes; and radicals of the formula:##STR72## wherein p=--CO--, --SO₂ --, --O--, --S--; or C.sub.(1-5)alkane, and preferably, --CH₂ -- so that the sulfoneimide remainsaromatic. Comparable polymers, usable in blends of the sulfonamides, aredescribed in U.S. Pat. No. 4,107,147, which we incorporate by reference.U.S. Pat. No. 3,933,862 describes other aromatic dithio dianhydrides.

7. Polyamides

We prepare linear or multidimensional polyamides (i.e., arylates ornylons) by condensing dicarboxylic acid halides (i.e., a diacid or adibasic acid) with diamines in the presence of an acid halide end cap orextended amine end cap. These polyamides are analogous to the polyamideoligomers U.S. Pat. Nos. 4,876,326; 5,109,105; 4,847,333 describe.

We prepare multidimensional amides by condensing a nitro, amine, or acidhalide hub with suitable diamines, diacid halides, and the extendedamine end cap or the acid halide end cap to form oligomers of thegeneral formulae: ##STR73## wherein P=a residue of a diamine, Q=aresidue of a diacid halide, and ∂, ξ and w were previously defined.

Examples of proposed amide syntheses follow.

EXAMPLE 36

Prepare a multidimensional amide oligomer by reacting: ##STR74## underan inert atmosphere to yield: ##STR75##

EXAMPLE 37

Prepare another multidimensional amide oligomer by reacting: ##STR76##under an inert atmosphere to yield: ##STR77##

EXAMPLE 38

Prepare a multidimensional amide oligomer by reacting: ##STR78## (orsimply the acid hub, a diamine, and an acid halide end cap monomer)under an inert atmosphere to yield: ##STR79##

Competitive side reactions between the reactants in Example 38 willlikely hinder the yield of this product and will make isolation of theproduct difficult. We enhance yield by adding the reactants serially,which might impair the physical properties of the resulting oligomers orcomposites made from the oligomers.

EXAMPLE 39

Use a etheramine hub to make a multidimensional amide oligomer byreacting: ##STR80## under an inert atmosphere to yield: ##STR81##

EXAMPLE 40

Prepare a multidimensional amide using an extended anhydride end cap byreacting: ##STR82## under an inert atmosphere to yield: ##STR83##

EXAMPLE 41

React melamine with an extended anhydride end cap to yield: ##STR84##

EXAMPLE 42

Prepare another multidimensional amide oligomer by reacting about 1 moleof cyuranic acid halide with about 3 moles of phenylenediamine and about3 moles of the extended anhydride end cap to yield: ##STR85##

We expect better yield of the fully substituted hub by reacting theanhydride with aminobenzoic acid and converting the free carboxylic acidfunctionality to an amine followed by condensation of the resultingextended amine with the acid halide hub.

8. Polyesters

We prepare polyesters by condensing the previously described diacidhalides and diols. The linear oligomers are four functional analogs ofthose compounds described in U.S. patent application Ser. No.07/137,493. We make multidimensional polyesters using phenol or acidhubs (particularly cyuranic acid) with suitable diols and diacidhalides. These multidimensional polyester oligomers are analogs of thosecompounds described in U.S. patent application Ser. Nos. 07/167,656 and07/176,518 or in U.S. Pat. Nos. 5,175,233 and 5,210,213. We prefer touse a thallium catalyst when making multidimensional polyesters toensure complete addition on the hub.

Commercial polyesters, when combined with well-known dilutents, such asstyrene, do not exhibit satisfactory thermal and oxidative resistance tobe useful for aircraft or aerospace applications. Polyarylesters (i.e.,arylates) are often unsatisfactory. These resins often aresemicrystalline, making them insoluble in laminating solvents,intractable in fusion, and subject to shrinking or warping duringcomposite fabrication. Those polyarylesters that are soluble inconventional laminating solvents often remain soluble in these samesolvents in composite form, thereby limiting their usefulness inaerospace structural composites. The high concentration of ester groupscontributes to resin strength and tenacity, but also makes the resinsusceptible to the damaging effects of water absorption. High moistureabsorption by commercial polyesters can lead to distortion of thecomposite when it is loaded at elevated temperature.

We prepare high performance, aerospace, polyester advanced composites,however, using crosslinkable, end capped polyester imide ether sulfoneoligomers that have an acceptable combination of solvent resistance,toughness, impact resistance, strength, processability, formability, andthermal resistance. By including Schiff base (--CH═N--), imidazole,thiazole, or oxazole linkages in the oligomer chain, the linear,advanced composites can have semiconductive or conductive propertieswhen appropriately doped.

Preferred linear polyethers or polyesters have the general formula:##STR86## wherein ξ=a crosslinkable end cap to improve the solventresistance of the cured oligomer in the advanced composite; and

A and B=linear residues of respective diacid halides and diols;

∀=ether or ester; and

t=0-27 (i.e., it is the "polymerization factor").

Generally, A and B are linear aromatic moieties having one or morearomatic rings, such as phenylene, biphenylene, naphthylene, orcompounds of the general formula:

    --.O slashed.--λ--.O slashed.--

wherein λ is any of --CO--; --O--; --S--; --SO₂ --; --(CH₃)₂ C--;--(CF₃)₂ C--; --CH═N--; oxazole, imidazole, or thiazole. For mostapplications, the linking groups will be selected from --SO₂ --, --S--,--O--, --CO--, --(CH₃)₂ C--, and --(CF₃)₂ C--. The oligomer usually is apolyester imide ether sulfone.

A or B preferably have the general formula:

    --.O slashed.--Ω--.O slashed.--Ψ--.O slashed.--Ω--.O slashed.--

wherein

Ω=--O--, --SO₂ --, or --S--, provided that Ω=--SO₂ -- only if Ψ=--SO₂--;

Ψ=--CO-- or --SO₂ --; and

.O slashed.=phenylene.

We usually prepare these polyester oligomers by reacting:

2 moles of a crosslinkable end cap acid halide;

n moles of an aromatic diacid halide or of a difunctional chainincluding a plurality of aryl rings linked with at least one linkageselected from the group consisting of --SO₂ --, --O--, --S--, --CO--,--(CH₃)₂ C--, --(CF₃)₂ C--, or mixtures thereof throughout the chain,the chain having an acid halide functionality on each end; and

n+1 moles of an aromatic bisphenol (i.e., a diol having terminal --OHfunctionalities

or by reacting:

2 moles of a crosslinkable phenol end cap;

n+1 moles of an aromatic diacid halide or of a difunctional chainincluding a plurality of aryl rings linked with at least one linkageselected from the group consisting of --SO₂ --, --O--, --S--, --CO--,--(CH₃)₂ C--, --(CF₃)₂ C--, or mixtures thereof throughout the chain,the chain having an add halide functionality on each end; and

n moles of an aromatic bisphenol.

We have previously described the suitable diacid and diol reactants.

Because the aromatic polyester resins synthesized in accordance withthis invention have appreciable molecular weight between the reactivegroups, even in thermoset formulations, the oligomers will retainsufficient plasticity to be processable during fabrication prior tocrosslinking of the end caps to thermoset composites. If possible, wesynthesize thermoplastic formulations with even higher molecularweights. The polyesters preferably have MWs between about 5000-40,000,and, more preferably, between about 15,000-25,000.

We make a particularly preferred polyester oligomer of the presentinvention by condensing a diacid halide with an excess of a diol to forman extended diol having intermediate ester linkages. This extended diolis then reacted with excess 4,4'-dichlorodiphenylsulfone to yield asecond intermediate dihalogen. The dihalogen can be condensed with aphenol end cap or the caps can be added in two steps by reacting thedihalogen with (H₂ N)₂ --.O slashed.--OH followed by reacting thetetra-amine intermediate (i.e., bis(2,4-diaminophenyl)ether) with anacid halide end cap from our U.S. Pat. No. 5,087,701. We prefer nadiccaps. This stepwise reaction is illustrated then, as follows: ##STR87##and, particularly, ##STR88##

In this sequential or step-wise synthesis, the caps effectively become:##STR89## when the acid halide caps condense with the free terminalamines on the extended ether/ester backbone (i.e., Cmpd. 3). Similarstepwise syntheses are available for reaction sequences that can produceterminal acid halides (--COX), phenols (--OH), or halides (--X), as willbe understood from this single example. Preferably, steps 2 and 3 aredone simultaneously by combining the diol of step 1 with the dihalogenand diaminophenol in a single reaction flask.

Although illustrated in four steps, isolation and transfer between stepsis unnecessary until the product forms. An acid acceptor is addedincrementally at each step along with the sequential monomer reactant.The product is isolated by precipitation in water with water washingthereafter. The product is a phenoxy phenyl sulfone alternating,diester. Preferred diacid halides have D as ##STR90## The preferreddiols are those where A is ##STR91##

We can achieve glass transition temperatures of about 950° F. (510° C.),although we can easily tailor the properties of the resulting oligomerswithin broad ranges.

Preferred multidimensional ether or ester oligomers have a central,aromatic hub and three, radiating, ether or ester chains, as shown inthe general formula: ##STR92## wherein ∀=ether or ester; ##STR93## R=alinear hydrocarbon radical, generally including ether andelectronegative ("sulfone") linkages selected from the group consistingof --SO₂ --, --S--, --(CH₃)₂ C--, --CO--, and --(CF₃)₂ C--, andgenerally being a radical selected from the group consisting of:##STR94## n=an integer such that the average molecular weight of--R--T-- is up to about 3000 (and preferably 0 or 1);

q=--CO--, --SO₂ --, --(CF₃)₂ C--, --(CH₃)₂ C--, or --S--; and

ξ=is a residue of multiple chemically functional acid halide end cap orphenol end cap monomer;

We prepare multidimensional ether or ester oligomers of this type byreacting substantially stoichiometric amounts of a multi-substitutedhub, such as trihydroxybenzene (i.e., phloroglucinol), withchain-extending monomers and crosslinking end cap monomers. Suitablechain-extending monomers include dicarboxylic acid halides, dinitrocompounds, diols (i.e., dihydric phenols, bisphenols, or dialcohols), ordihalogens, in the same manner as making linear ethers or esters.

Multidimensional Polyol Hubs

The hub may be a polyol such as phloroglucinol or thosetris(hydroxyphenyl)alkanes described in U.S. Pat. No. 4,709,008 of thegeneral formula: ##STR95## wherein R₁₅ is hydrogen or methyl and can bethe same or different. These polyols are made by reacting, for example,4-hydroxybenzaldehyde or 4-hydroxyacetophenone with an excess of phenolunder acid conditions (as disclosed in U.S. Pat. Nos. 4,709,008;3,579,542; and 4,394,469). We generally react the polyols withnitrophthalic anhydride, nitroaniline, nitrobenzoic acid, or a diacidhalide to form the actual reactants (i.e., amines or acid halides) thatare suitable as heterocycle hubs, as will be understood by those ofordinary skill.

We can use the extended acid hub: ##STR96## that we described earlier.This hub is characterized by an intermediate ether and imide linkageconnecting aromatic groups. Thio-analogs are also contemplated, inaccordance with U.S. Pat. No. 3,933,862. Other acid or polyol hubs areequally suitable.

Generally the ratio of reactants is about 1 mole of the hub to at least3 moles of end cap to at least 3 moles of polyaryl arms. The armsusually include phenoxyphenyl sulfone, phenoxyphenyl ether, or phenylsulfone moieties to supply the desired impact resistance and toughnessto the resulting advanced composite (through "sulfone" swivels) withoutloss of the desired thermal stability.

A second synthetic mechanism for making the multidimensional etheroligomers involves the reaction of a halogenated or polynitro aromatichub with suitable amounts of diols and an extended acid halide end capmonomer. Again, the reactants are mixed together and are generallyreacted at elevated temperatures under an inert atmosphere. Generallyfor either mechanism, the reactants are dissolved in a suitable solventsuch as benzene, toluene, xylene, DMAC, or mixtures and are refluxed topromote the reaction. We sometimes add TEA to catalyze the reaction.

We also can make suitable oligomers by directly reacting polyol hubs(such as phloroglucinol) or halogenated aromatic hubs directly with endcap groups having the corresponding halide, acid halide, or alcohol(phenol) reactive functionality.

Schiff base diols are prepared by the condensation of aldehydes andamines under the general reaction schemes: ##STR97##

We prepare suitable dinitro compounds by reacting nitrophthalicanhydride (as described in U.S. Pat. Nos. 4,297,474 and 3,847,869) witha diamine. In this case, suitable diamines include those describedpreviously.

We prefer arms in the multidimensional oligomers that are short chainshaving formula weights below about 1500 per arm, and, preferably, about500 per arm. Solubility of the oligomers becomes an increasing problemas the length of the backbones (arms) increases. Therefore, we prefershorter backbones, so long as the resulting oligomers remainprocessable. That is, the backbones should be long enough to keep theoligomers soluble during the reaction sequence.

We also can make noncrosslinking ether or ester linear ormultidimensional polymers for blends by the same synthetic methods asthe oligomers with the substitution of a quenching cap for thecrosslinking end cap. For example, phenol benzoic acid, or nitrobenzenecan be used to quench (and control MW).

The following are examples of proposed ester syntheses.

EXAMPLE 43

Prepare an ester star oligomer by dissolving phloroglucinol dihydrate ina solution of H₂ O and a solvent containing 27% xylene and 73% DMAC. Ina Barrett trap under a bubbling N₂ atmosphere, reflux the mixture tostrip off the H₂ O and, then, the xylene. After the stripping step, coolthe resulting DMAC solution slowly to about 0° C. before addingtriethylamine (TEA) (30% excess) while stirring the solution. After 10min. of stirring, add an acid halide end cap monomer, and rinse theproduct with DMAC. Continue stirring for 2 hours, before recovering aproduct by adding a suitable amount of HCl.

EXAMPLE 44

Prepare another ester star oligomer by dissolving phloroglucinoldihydrate in a xylene/DMAC mixture having about 740 g xylene and 2000 gDMAC. Reflux the mixture in a Barrett trap under a N₂ atmosphere tostrip H₂ O, which the reaction generates. Upon heating to about 160° C.,strip the xylene from the mixture. Cool the DMAC solution to ambient,and add a phenol end cap monomer and TEA. Stir the resulting mixture inan ice bath while adding the acid chloride ofbis-(4,4'-carboxyphenoxyphenylsulfone) is slowly. After the addition,continue stirring for 2 hr. The product is soluble in the reactionmixture, but coagulates in H₂ O to a powder. Wash the powder withdeionized water to remove residual chloride.

We have found that, when reacting, for example, phloroglucinol with anacid chloride end cap in DMAC and TEA that the resulting product is amixture of di- and tri- substituted multidimensional ester oligomers.The condensation is difficult to drive to completion (i.e., replacementof all the --OH groups) to yield the desired product. We improve theyield of fully reacted multidimensional ester, however, by replacing theTEA with thallium ethoxide (Tl--OC₂ H₅). While thallium ethoxide ispreferred, it is possible that any lower alkoxy or aryloxy substituenton the metal will be active as a catalyst. That is, methoxy, propoxy,isopropoxy, n-butoxy, phenoxy, or the like may also display catalyticactivity.

Since the multidimensional polyester oligomers that we synthesize areoften used without isolation of products (so we have complex mixtures inthe prepreg), we believe that the new product made using a thalliumcatalyst, richer in the truly multidimensional ester product, will yieldbetter composites than we achieved with the mixture of fully andpartially reacted hubs that results when using TEA as a catalyst. Ineffect, the product is a blend of a linear and a multidimensionaloligomer when the reaction is incomplete.

The method of using a thallium catalyst is equally applicable when usingan acid halide hub such as cyuranic acid chloride with an extendedphenol end cap monomer.

We believe that Tl--OC₂ H₅ will produce a higher yield of thetrisubstituted hub. If the hub has more than three reactive hydroxyl oracid halide functionalities, the thallium ethoxide catalyst will promotemore complete reaction (or substitution) than TEA.

9. Polyethers

We prepare polyethers or ethersulfones by condensing dinitro compoundsor dihalogens and diols or by other conventional ether syntheses using aphenol end cap monomer or a halogeno end cap monomer.

We can use any previously described dihalogen.

We can prepare dinitro compounds by reacting nitrophthalic anhydridewith the diamines, as we previously described. Of course, we can preparedihalogens in the same way by replacing the nitrophthalic anhydride withhalophthalic anhydride. We can condense nitroaniline, nitrobenzoic acid,or nitrophenol with dianhydrides, diacid halides, diamines, diols, ordihalogens to prepare other dinitro compounds that include amide, imide,ether, or ester linkages between the terminal phenyl radicals and theprecursor backbones. The synthesis of the dinitro compounds ordihalogens can occur prior to mixing the other reactants with thesecompounds or the steps can be combined in suitable circumstances todirectly react all the precursors into the oligomers. For example, wecan prepare a polyarylether oligomer by simultaneously condensing amixture of the phenol end cap, nitrophthalic anhydride, phenylenediamine, and HO--.O slashed.--O--.O slashed.--O--.O slashed.--O--.Oslashed.--OH.

We can prepare a multidimensional ether by the simultaneous condensationof phloroglucinol with a dihalogen and a phenol end cap monomer. Thoseof ordinary skill will recognize the range of possible multidimensionalpolyether oligomers from this simple example.

We can also synthesize multidimensional oligomers of the formula:##STR98## with an Ullmann aromatic ether synthesis followed by aFriedel-Crafts reaction, as will be further explained.

Here, R₁₆ is ##STR99## q=--SO--, --CO--, --S--, or --(CF₃)₂ C--, andpreferably --SO₂ --, or --CO--.

To form the oligomers for formula (XIX), preferably a halosubstitutedhub is reacted with phenol in DMAC with a base (NaOH) over a Cu Ullmanncatalyst to produce an ether "star" with active hydrogens para- to theether linkages. End caps terminated with acid halide functionalities canreact with these active aryl groups in a Friedel-Crafts reaction toyield the desired product. For example, we react 1 mole oftrichlorobenzene with about 3 moles of phenol in the Ullmann etherreaction to yield an intermediate of the general formula: .Oslashed..brket open-st.O--.O slashed.!₃ which we, then, react with about3 moles of the extended acid halide end cap to produce the final,crosslinkable, ether/carbonyl oligomer.

Similarly, to form the oligomers of formula (XIX), the hub is extendedpreferably by reacting a halo- substituted hub with phenol in theUllmann ether synthesis to yield the ether intermediate of the .Oslashed..brket open-st.O--.O slashed.!₃ compounds. This intermediate ismixed with the appropriate stoichiometric amounts of a diacid halide ofthe formula XOC--R₁₆ --COX and an end cap of the formula (Z)₂ --.Oslashed. formula (XX)! in the Friedel-Crafts reaction to yield thedesired, chain-extended ether/carbonyl star and star-burst oligomers. Weprepare end caps of this type by reacting 2 moles of Z--COOH or its acidhalide with .O slashed..paren open-st.NH₂)₂.

We can use coreactants with the ether or ethersulfone oligomers orcoreactive oligomer blends that include these oligomers, includingp-phenylenediamine; 4,4'-methylenedianiline; benzidine; loweralkyldiamines; or compounds of the general formula: ##STR100## whereinR₁₇ =hydrogen, lower alkyl, or aryl; and

R₁₈ =lower alkyl (having about 2-6 carbon atoms) or aryl.

Coreactants of this same general type are also probably usable with theamideimides or etherimides.

EXAMPLE 45

Prepare an ether star oligomer by charging DMAC, xylene, K₂ CO₃, and amultiple chemically functional phenol end cap to a reaction flask fittedwith a stirrer, condenser, thermometer, and N₂ purge. Add phloroglucinoldihydrate and reflux the mixture until all H₂ O in the flask is expelledand no additional H₂ O is generated. After cooling the resultingintermediate mixture, add about 3.0 moles of4,4'-dichlorodiphenylsulfone and reheat the flask to about 150° C. tostrip the xylene from the solution. Continue refluxing for 16 hours atabout 150° C. Upon removal of all the xylene, heat the flask to about160°-164° C. for 2 more hours. After cooling, recover the product byadding H₂ O to induce coagulation while mixing the solution in a Waringblender. Wash the coagulate thoroughly with deionized water until theresidual chloride is removed.

10. Polyaryl Sulfide Oligomers (PPS)

We can also prepare multiple chemically functional oligomers of thepresent invention for PPS backbones. These four functional oligomers areanalogs of the reactive PPS oligomers we described in U.S. patentapplication Ser. No. 07/639,051.

A brief description of the state of the art for PPS resins is anappropriate introduction.

Edmonds U.S. Pat. No. 3,354,729 describes the preparation ofpoly(arylene sulfide) polymers by the reaction of an alkali metalsulfide with a polyhalo-substituted aromatic (preferablydihaloaromnatic) compound wherein the halogen atoms are attached to ringcarbon atoms in a polar organic compound at elevated temperature. Acopper compound, such as cuprous and cupric sulfides, or halides, may bepresent to aid in the formation of the polymer. Molecular weight of thepolymer is increased by heat treatment, either in the absence of oxygenor with an oxidizing agent. Molecular weight is increased due tocrosslinking, lengthening of the polymer chain, or both.

Campbell U.S. Pat. No. 3,919,177 discloses the preparation ofp-phenylene sulfide polymers by reacting p-dihalobenzene, a suitablesource of sulfur, an alkali metal carboxylate, and a preferably liquidorganic amide. Both of the alkali metal carboxylate and the organicamide components serve as polymerization aids. The alkali metalcarboxylate may typically be lithium acetate, lithium propionate, sodiumacetate, potassium acetate, or the like. The organic amide may typicallybe formamide, acetamide, N-methylformamide, or N-methyl-2-pyrrolidone(NMP). A variety of sulfur sources can be used, including alkali metalsulfides, thiosulfates, thiourea, thioamides, elemental sulfur, carbondisulfide, carbon oxysulfide, thiocarbonates, thiocarbonates,mercaptans, mercaptides, organic sulfides, and phosphorus pentasulfide.

Crouch et al. U.S. Pat. No. 4,038,261 describes a process for thepreparation of poly(arylene sulfide)s by contacting p-dihalobenzene, apolyhalo aromatic compound having greater than two halogen substituents,an alkali metal sulfide, lithium carboxylate or LiCl, NMP, and an alkalimetal hydroxide. The use of a polyhalo compound results in the formationof a branched chain polymer of reduced melt flow that can be spun intofibers. The alkali metal sulfide can be charged to the reaction inhydrated form or as an aqueous mixture with an alkali metal hydroxide.

Gaughan U.S. Pat. No. 4,716,212 describes the preparation ofpoly(arylene sulfide ketone)s by reaction of a polyhalobenzophenone suchas 4,4'-dichlorobenzophenone and a mixture of sodium hydrosulfide andsodium hydroxide.

Satake et al. U.S. Pat. Nos. 4,895,892 and 4,895,924 both disclose meltstable poly(arylene thioether ketone)s. The '892 patent describes blendsof an arylene thioether ketone polymer with a thermoplastic resin suchas poly(arylene thioether)s, aromatic polyether ketones, polyamides,polyamideimides, polyesters, polyether sulfones, polyether imides,poly(phenelyene ether)s, polycarbonates, polyacetals, fluoropolymers,polyolefins, polystryrene, polymethyl methacrylate, ABS, and elastomerssuch as fluororubbers, silicone rubbers, polyisobutylenes, hydrogenatedSBR, polyamide elastomers and polyester elastomers. U.S. Pat. No.4,895,924 discloses the preparation of poly(arylene thioetherketone)fibers by melt spinning of polymers and blends of the type disclosed inU.S. Pat. No. 4,895,892.

Blackwell U.S. Pat. No. 4,703,081 describes a ternary polymer alloycomprising a poly(arylene sulfide), a poly(amideimide) and a poly(arylsulfone). The poly(arylene sulfide) is prepared, for example, byreaction of p-dichlorobenzene and sodium sulfide in NMP. Various otherdi- and tri- halo aromatics are mentioned as monomers for use in thepreparation of the poly(arylene sulfide)s.

Johnson et al. U.S. Pat. No. 4,690,972 describes the preparation ofpoly(arylene sulfide) compositions by incorporating additives whichaffect the crystalline morphology, followed by heating and coolingsteps. Among the preferred arylene sulfides are poly(phenylene sulfide)and poly(phenylene sulfide ketone). The additive is preferably apoly(arylene ether ketone) such as 1,4-oxyphenoxy-p,p'-benzophenone.

Leland et al. U.S. Pat. No. 4,680,326 describes poly(arylene sulfide)compositions having a combination of good cracking resistance andelectrical insulation resistance. The compositions include a reinforcingmaterial, polyethylene, and an organosilane.

Skinner U.S. Pat. No. 4,806,407 describes blends of p-phenylene sulfidepolymers and melt extrudable polymers such as non-halogenated polymersand copolymers of olefins, halogenated homopolymers (polyvinylidenefluoride, polyvinyl chloride, polychlorotrifluoroethylene, and thelike), ethylene/acrylic copolymers (e.g., "Surlyn"), and both aromaticand aliphatic polyamides.

We incorporate these PPS patents by reference.

The present invention provides oligomers useful in the preparation ofpoly(arylene sulfide) PPS! polymers having favorable thermomechanicaland thermo-oxidative properties, having other advantageous performanceproperties, and having favorable processing characteristics in thepreparation of such composites. The composites have high solventresistance, moisture resistance, toughness, and impact resistance.

We react (n) equivalents of a dihaloaromatic compound, (n+1) equivalentsof a sulfur compound that is reactive with the dihaloaromatic compoundsto form thioethers, and 2 equivalents of the halogeno (i.e., halide) endcap monomer to obtain an oligomer corresponding to the formula:##STR101## where: Ar and Ar₁ are arylene;

μ is an integer such that the oligomer has about molecular weight ofbetween about 500 and about 40,000;

ξ is a residue of a halogeno end cap monomer, and

the other variables are as previously defined.

We prepare composites from the oligomers in the form of films, coatings,moldings, fibers, and other structures useful in engineeringapplications. We expect that PPS composites produced from theseoligomers will exhibit exceptional toughness and impact resistance forPPS.

When used for preparation of various forms of polymer products, theoligomers of the invention exhibit especially favorable processingcharacteristics. Their melt and plastic flow properties are especiallyadvantageous for the preparation of moldings and composites without thenecessity of solvents. Because the oligomers crosslink by an addition of"step growth" mechanism, curing of moldings or composites can beconducted without significant outgassing of solvents or condensationproducts, thereby yielding polymer products of exceptional structuraland dimensional integrity. Adhesives comprising the oligomers of theinvention, and the polymeric products obtained by curing thereof, we canprepare without outgassing of either reaction products or solvents.

The oligomers are crosslinkable by addition or step growth reaction ofthe unsaturated moieties of the end caps analogous to the PPS oligomersof 07/639,051. In this respect they differ from the polymers of U.S.Pat. No. 3,354,129, which are crosslinked through functional groupsprovided in the linear backbone, and from the polymers of U.S. Pat. No.4,038,261, in which linear chains are branched and crosslinked byincorporation of a minor proportion of trihaloaromatic compound in apolymerization mixture comprising p-dihalobenzene and sulfur compound.

We can prepare oligomers of the present invention in both linear andmultidimensional form. We prepare the linear oligomers by reacting nequivalents of a dihaloaromatic compound (i.e., a dihalogen), n+1equivalents of a sulfur compound that is reactive with thedihalo-aromatic compounds to form thioethers, and 2 equivalents ofhalogeno end cap monomer. Crosslinking of the oligomer may subsequentlytake place under curing conditions. The multidimensional oligomers, ofcourse, use an appropriate hub.

Generally, the sulfur compound used in the preparation of the oligomeris characterized by its reactivity with halo organic compounds toproduce thioethers. Preferably, the sulfur compound comprises an alkalimetal sulfide, an alkali metal sulfohydride, or an alkali metalbisulfide. Among the various other sulfur compounds which may optionallybe used in the reaction are alkali metal thliosulfates, thioamides,elemental sulfur, carbon disulfide, carbon oxysulfide, thiocarbonates,thiocarbonates, mercaptans, mercaptides, organic sulfides and phosphoruspentasulfide. If the sulfur compound used is other than an alkali metalsulfide or bisulfide, we include a base in the reaction charge. If thesulfur compound is an alkali metal bisulfide, the use of a base is notstrictly necessary, but we prefer to include it. If the sulfur compoundis an alkali metal sulfide, a base is unnecessary.

For the PPS synthesis, preferred dihalogens include:

1,2-dichlorobenzene

1,3-dichlorobenzene

1,4-dichlorobenzene

2,5-dichlorotoluene

1,4-dibromobenzene

1,4-diodobenzene

1,4-difluorobenzene

2,5-dibromoaniline

1,4-di-n-butyl-2,5-dichlorobenzene

1,4-di-n-nonyl-2,6-dibromobenzene

2,5-dichlorobenzamide

1-acetamido-2,4-dibromoanphthalene

4,4'-dichlorobiphenyl

p-chlorobromobenzene

p,p'-dichlorodiphenylether

o,p'-dibromodiphenylamine

4,4'-dichlorobenzophenone and 4,4'-dichlorodiphenylsulfone.

We could use any dihalogen we described earlier.

Preparation of the oligomer is preferably carried out in the presence ofa polymerization aid such as a liquid organic amide, a carboxylic acidsalt, or both. In the preparation of conventional poly(arylene sulfide)polymers, such aids are effective in increasing the average MW of thepolymerization product. In the process of the invention, suchpolymerization aids are effective in controlling and limiting themolecular weight distribution within a narrow range of variability.

Conditions for carrying out the reaction to form the oligomer areessentially the same as those described in U.S. Pat. Nos. 3,354,129 and3,919,177. The reaction may be carried out, for example, by contactingthe dihalogen, the sulfur compound, and the end cap monomer in a polarsolvent at a temperature of from about 125° to about 450° C., preferablyfrom about 175° to about 350° C. The amount of polar solvent may varyover a wide range, typically from about 100 to about 2500 ml per mole ofthe sulfur compound.

Alkali metal carboxylates that may be employed in the reaction generallycorrespond to the formula:

    R.sub.20 COO(M.sub.3)

where R₂₀ is a hydrocarbyl radical selected from alkyl, cycloalkyl, andaryl and combinations thereof such as alkylaryl, alkylcycloalkyl,cycloalkylalkyl, arylalkyl, arylcycloalkyl, alkylarylakyl andalkylcycloalkylalkyl, the hydrocarbyl radical having 1 to about 20carbon atoms, and M₃ is an alkali metal selected from the groupconsisting of lithium, sodium, potassium, rubidium and cesium.Preferably, R₂₀ is an alkyl radical having 1 to about 6 carbon atoms ora phenylene radical. Most preferably, it is phenylene. M₃ is lithium orsodium, most preferably lithium. If desired, employ the alkali metalcarboxylate as a hydrate or as a solution or dispersion in water.

Examples of some alkali metal carboxylates that we might use in theprocess include lithium acetate, sodium acetate, potassium acetate,lithium propionate, sodium propionate, lithium 2-methylpropionate,rubidium butyrate, lithium valerate, sodium valerate, cesium hexanoate,lithium heptanoate, lithium 2-methyloctanoate, potassium dodecanoate,rubidium 4-ethyltetradecanoate, sodium octadecanoate, lithiumcyclohexanecarboxylate, cesium cyclododecanecarboxylate, sodium3-methlcyclopentanecarboxylate, potassium cyclohexylacetate, potassiumbenzoate, lithium benzoate, sodium benzoate, potassium m-toluate,lithium phenylacetate, sodium 4-phenylcyclohexanecarboxylate, potassiump-tolylacetate, lithium 4-ethylcyclohexylacetate, and the like, ormixtures thereof.

The organic amides used in the method of this invention should besubstantially liquid at the reaction temperatures and pressures.Examples of some suitable amides are N,N-dimethylformamide,N,N-dipropylbutyramide, N-methyl-ξ-caprolactam,hexamethyl-phosphoramide, tetramethylurea, and the like, or mixturesthereof.

When we use alkali metal carboxylates and organic amides for control ofthe oligomer formation reaction, we carry out the reaction at about 235°C. and about 450° C., preferably about 240° C. to about 350° C. When thealkali metal carboxylate is a sodium, potassium, rubidium, or cesiumsalt of an aromatic carboxylic acid, i.e., an acid in which the carboxylgroup is attached directly to an aromatic nucleus, the temperatureshould be within the range of from about 255° C. to about 450° C.,preferably from about 260° C. to about 350° C. The reaction time iswithin the range of from about 10 minutes to about 3 days and preferablyabout 1 hour to about 8 hours. Preferably, we use about 0.5 to about 2moles metal carboxylate compound per mole of the dihaloaromaticcompound. When we use NMP as the organic amide component of the reactorcharge, we use it in substantially equal molar proportion with thedihalogen compound.

We use the PPS oligomers in melt or solution form for the preparation offilms, moldings, and composites. Curing at a temperature in the range ofbetween about 480° and about 640° F. (250° to 340° C.) causes stepgrowth reaction between the unsaturated moieties of the end groups,resulting in the formation of high molecular weigh polymers havingsuperior thermal and mechanical properties and solvent resistance. Weinitiate the curing reaction either thermally or chemically. Where theoligomer has a relatively high molecular weight, for example, greaterthan 10,000, preferably about 15,000 to 25,000, the polymer produced oncuring is thermoformable. Where the molecular weight is below 10,000,especially in the range of between about 1000 and about 6000, the curedresin is likely a thermoset material, which we seek to avoid.

We prepare multidimensional PPS oligomers by reacting w(n) equivalentsof a dihalogen, w(n+1) equivalents of a sulfur compound that is reactivewith dihalogen to form thioethers, one equivalent of a polyhalo hubhaving w halogen substituents, and w equivalents of a halogeno end capmonomer.

In the preparation of either linear or multidimensional PPS oligomers,it is generally preferred that the dihalogen comprises a dihalobenzenesuch as, for example, p-dichlorobenzene or m-dichlorobenzene, and thesulfur compound be an alkali metal sulfide such as sodium sulfide, whichcan be prepared in situ by reaction of an alkali metal hydrosulfide anda base. An advantageous method for the preparation of arylene sulfideoligomers from an alkali metal hydrosulfide is described in U.S. Pat.No. 4,716,212.

We can make blends suitable for composites, for example, by mixing a PPSoligomer of the invention with a macromolecular or oligomeric polymerthat is essentially incapable of crosslinking with the crosslinkableoligomer. Such blends merge the desired properties of crosslinkingoligomers and non-crosslinking polymers to provide tough, yetprocessable, resin blends. We can use a variety of macromolecular oroligomeric polymers, most typically a poly(arylene sulfide) prepared byreaction of a dihalogen with a sulfur compound of the type used in thepreparation of the oligomer, the reaction being quenched with a suitablenon-crosslinking terminal group. Generally, we would prepare suchpoly(arylene sulfide)s by the methods described in U.S. Pat. Nos.3,354,129, 3919,177, and 4,038,261. Most preferably, we would preparethe non-crosslinking polymer and crosslinkable oligomer from the samedihaloaromatic and sulfone compound, thus enhancing compatibilitybetween oligomer and polymer. The quenching agent is typically amonohaloaromatic compound such as chlorobenzene.

The blends also encompass the advanced composites blends of poly(arylenesulfide) oligomers blended with poly(amide imide)s and poly(arylsulfone)s analogous to the blends described in U.S. Pat. No. 4,703,081.Blends may also comprise the various polymers used in the blendsdescribed in U.S. Pat. No. 4,595,892.

The melt flow characteristics of PPS oligomers are such that PPS may beused in melt rather than solution form in various applications,including the preparation of composites. In this regard, PPS is similarto the heterocycle liquid crystals.

For maximum mechanical properties of coatings or composites preparedfrom PPS oligomers or blends, we prefer that the halogeno substituentsof the dihalogen have a predominantly p-orientation. For processability,however, the most favorable results are generally provided by use of them-isomer, so processing and final properties compete, forcing a tradewhen designing the formulation. The m-isomer may also be preferable foradhesives. In certain instances, it may be advantageous to provide ablend of m- and p-isomers having a mix of properties tailored to theparticular application of the cured oligomer.

The end cap monomer can be ##STR102## (i.e., a pyrimidine cap) whenmaking these PPS oligomers or their related polyethers.

The following examples illustrate the invention with respect to PPSoligomers.

EXAMPLE 46

Place hydrated Na₂ S in N-methylpyrrolidone (NMP) in a glass reactionflask and heat to 160° C. while the flask is flushed with nitrogen for atime sufficient to dehydrate the Na₂ S. Add p-dichlorobenzene (88.2 g)and a halogeno end cap monomer to the dehydrated solution, and theresulting mixture is sealed in a glass tube. The mixture contained inthe tube is heated at 230° C. for 45 hours, then at 225° C. for 20hours, and then at 260° C. for 24 hours. A product precipitating fromthe reaction mixture comprises a four functional PPS oligomer.

EXAMPLE 47

Prepare a multidimensional PPS oligomer by reaction of Na₂ S,p-dichlorobenzene, 1,3,5-trichlorobenzene, and a halogeno end capmonomer. The preparation procedure is substantially as described inExample 51, except that the trichlorobenzene is added together with thep-dichlorobenzene and the end cap.

11. Carbonates

We prepare multiple chemically functional carbonate oligomers byreacting a diol (sometimes also referred to as a dihydric phenol), acarbonyl halide, and a phenol end cap in a manner similar to thereaction described in U.S. Pat. No. 4,814,421, which is incorporated byreference. While we can use any diol, we prefer diols having theformula:

    HO--.O slashed.--A--.O slashed.--OH

wherein A is

(i) a divalent hydrocarbon radical containing 1-15 carbons,

(ii) a halogen substituted divalent hydrocarbon radical containing 1-15carbons, or

(iii) divalent groups such as --S--, --SS--, --SO₂ --, --SO--, --O--, or--CO--.

We prefer the aromatic diols, especially the diol: HO--.O slashed.--SO₂--.O slashed.--OH.

The carbonyl halide is a carbonate precursor and commonly is phosgene,but the reaction can also use a diarylcarbonate or a bishaloformate of adihydric phenol or of a glycol.

The reaction proceeds by interfacial polymerization as described in U.S.Pat. Nos. 3,028,365; 3,334,154; 3,275,601; 3,915,926; 3,030,331;3,169,121; 3,027,814; and 4,188,314, which are incorporated byreference. Generally the phenol reactants are dissolved or dispersed inaqueous caustic, adding the mixture to a water immiscible solvent, andcontacting the reactants thereafter with the carbonate precursor in thepresence of a catalyst and under controlled pH conditions.

The catalyst is usually a tertiary amine (like TEA), quaternaryphosphonium compounds, or quarternary ammonium compounds.

The water immiscible solvents include methylene chloride,1,1-dichloroethane, chlorobenzene, toluene, or the like.

The reaction can also be used to make mono- and difunctionalpolycarbonate oligomers by substituting an imidophenol end cap monomerfrom our U.S. Pat. Nos. 4,980,481; 4,661,604; 4,739,030; and 5,227,461for the four functional phenol end cap monomer. The difunctionalimidophenol end cap monomers have the general formula: ##STR103## whereE is an unsaturated hydrocarbon is previously defined.

We can prepare arylate/carbonate copolymers by the reaction of phosgenewith diacid halides in the solvent phase with a diol like bisphenol-A inthe solute phase using 3,5-di(nadicylimino)benzoyl chloride or theextended acid halide end cap monomer, and can prepare multidimensionalcarbonates using a suitable polyhydric hub like phloroglucinol.Multidimensional arylate/carbonates, of course, can use an acid or acidhalide hub, like cyuranic acid. Those skilled in the art will recognizethe mechanisms which are analogous to those for our other linear andmultidimensional oligomers.

Step wise condensation similar to the four-step process described forthe esters will also lead to carbonates. Here, a long-chain fourfunctional amine having intermediate, characteristic carbonate linkagesis formed by condensing the diol with a carbonyl halide and ##STR104##followed by reaction of the four terminal amines (i.e., two at each endof the chain in the carbonate compound): ##STR105## With an acid halideend cap monomer (see, e.g., U.S. Pat. No. 5,087,701) to yield the Zlinks of the characteristic four functional end caps.

12. Polyesteramides

The linear oligomers are characterized by having a pair of alternatingester linkages ##STR106## followed by a pair of alternating amidelinkages ##STR107## as generally illustrated for polymeric homologs inU.S. Pat. No. 4,709,004 or by having sequential amide/ester linkages.The preferred esteramides are prepared by condensing an amino/phenolcompound (like aminophenol; preferably, 4-2-p-hydroxyphenyl)isopropyl!-4'-amino diphenyl ether) or otheramino/phenols described in U.S. Pat. No. 4,709,004 with a diacid halide,especially terephthaloyl chloride, and four functional acid halide endcap monomer following generally the process of Imai et al. in J. PolymerSci., 1981, 19, pp. 3285-91 which is discussed in U.S. Pat. No.4,709,004 (both of which are incorporated by reference). We alter theImai process by using the end cap monomer to quench the reaction and toprovide an oligomeric product. In the preferred synthesis, the oligomeris likely to include a mixture of the following recurring units:##STR108## as the diacid halide reacts in a head-to-tail sequence orhead/head-tail/tail sequence.

Multidimensional esteramides condense a polybasic acid, polyol, orpolyamine hub with a suitable end cap monomer or with arm extenders,like the amino/phenol compounds, amino/acid compounds, diacid halides,and diamines, as appropriate and as previously described for the otherresin systems.

13. Cyanates and Cyanate Esters

We can also apply the technique of multiple chemically functionaloligomer to the cyanate resin system. Typical resins in the cyanatefamily are described in U.S. Pat. No. 5,134,421, which we incorporate byreference. Cyanate resins are characterized by the reactivefunctionality --OCN, but we use the term to include the thio cyanatecousins --SCN as well. Cyanate resins are prepared by reacting diols orpolyols (in the case of multidimensional morphology) with a cyanogenhalide, especially cyanogen chloride or bromide. The synthesis is wellknown and is described in U.S. Pat. Nos. 3,448,079; 3,553,244; and3,740,348, for example; each of which is also incorporated by reference.The cyanate functionality self-polymerizes to form cyanate esters eitherwith or without a suitable catalyst (such as tin octoate).

Therefore, to prepare linear cyanate oligomers of the present invention,diols are converted to dycanate (i.e., N.tbd.C--O--R₄ --O--C.tbd.N whereR₄ is the residue of an organic diol) in the presence of cyanogen halideand the phenol end cap monomers of formula (II) are also connected tothe corresponding cyanate using the same reaction. Then, the chainterminating cyanate end cap is mixed with the cyanate to control theself-polymerization which yields a cyanate ester having fourcrosslinking sites at each end. The multidimensional synthesis isanalogous but involves a polyol hub converted to the cyanate, mixed withthe dicyanate and cyanate end cap monomer, and polymerized.

Suitable catalysts for the cyanate resin systems of the subjectinvention are well known to those skilled in the art, and include thevarious transition metal carboxylates and naphthenates, for example zincoctoate, tin octoate, dibutyltindilaurate, cobalt naphthenate, and thelike; tertiary amines such as benzyldimethylamine andN-methylmorpholine; imidazoles such as 2-methylimidazole;acetylacetonates such as iron (III) acetylacetonate; organic peroxidessuch as dicumylperoxide and benzoylperoxide; free radical generatorssuch as azobisisobutyronitrile; organophoshines and organophosphoniumsalts such as hexyldiphenylphosphine, triphenylphosphine,trioctylphosphine, ethyltriphenylphosphonium iodide andethyltriphenylphosphonium bromide; and metal complexes such as copperbis 8-hydroxyquinolate!. Combinations of these and other catalysts mayalso be used.

Any diol we previously described can be converted to the cyanate analogand used in this synthesis. For high MWs, however, we prefer to use asoluble dicyanate, especially:

    NCO--.O slashed.--O--.O slashed.--SO.sub.2 --.O slashed.--O--.O slashed.--OCN

Similarly, any polyol hub we previously described can be converted tothe corresponding polycyanate analog to serve as the hub (∂) in thesynthesis of multidimensional cyanate ester oligomers.

The thiocyanates exhibit essentially the same chemistry.

14. Advanced Composite Blends

Advanced composite blends comprise at least one crosslinking oligomerand at least one polymer wherein the backbones of the oligomer(s) andpolymer(s) are from different chemical families. Such blends presentpromise for tailoring the mechanical properties of composites whileretaining ease of processing. At their simplest, the composites aremixed chemical blends of a linear or multidimensional crosslinkingoligomer of one chemical family, such as a imide, and a linear ormultidimensional polymer, unable to crosslink, from a different chemicalfamily, such as ethersulfone. Generally the polymer has a MW that isinitially higher than that of the oligomer, but the formula weight ofthe oligomeric portion of the blend will increase appreciably duringcuring through addition (i.e. homo-) polymerization between thecrosslinking functionalities. The ratio of oligomer(s) to polymer(s) canbe varied to achieve the desired combination of physical properties.Usually the ratio is such that the addition polymer (i.e., composite)formed during curing of the oligomer constitutes no more than about 50mol % of the total.

While two component blends are preferred, the blends can be more complexmixtures of oligomers or polymers with or without coreactants. Theblends may even include coreactive oligomers as will be explained (i.e.,diamines, diols, or ##STR109## resins). We can also form blends of thesemultiple chemically functional oligomers with correspondingmonofunctional or difunctional oligomers from our earlier patents andpatent applications.

The oligomer is preferably selected from imidesulfone; ethersulfone;cyanate ester; carbonate; amide; esteramide; imide; ether; ester;estersulfone; etherimide; or amideimide. That is, any of the oligomerswe have described.

In advanced composite blends oligomers or coreactive oligomer blends arefurther blended with a noncrosslinking polymer having a backbone from adifferent chemical family. The polymer can be from any one of thefamilies described for the oligomers, but the oligomeric and polymericbackbones must be different to form what we elect to call an advancedcomposite (i.e. mixed chemical) blend. The resulting blend may yield IPNor semi-IPN morphology in the consolidated resin (composite) state.

Preferably the polymer's MW initially is greater than that of theoligomer, because the MW of the oligomer in the cured composite willincrease through addition polymerization. The cured composite from anadvanced composite blend will have a blend of two, "long" molecules, andwill not suffer from a broad distribution of MWs or a mismatch of MWthat reduces the physical properties obtainable in some prior artblends, such as those Kwiatkowski suggested in U.S. Pat. No. 3,658,939.

Preferred oligomer/polymer combinations in the advanced composite blendsof this invention include: amideimide/imide; imide/amide; ester/amide;ester/imide; and ester/esteramide.

Advanced composite blends allow tailoring of the properties of highperformance composites. They allow averaging of the properties of resinsfrom different families to provide composites that do not have as severeshortcomings as the pure compounds. The resulting composites have ablending or averaging of physical properties, which makes themcandidates for particularly harsh conditions.

Although the concept of advanced composite blends is probably bestsuited to linear morphology, the advanced composite blends of thepresent invention also include multidimensional oligomers and polymers.We prefer linear morphology because the resulting composites havemixtures of polymers of relatively large and roughly equivalent MW. Theindividual polymers are similar in structure. We have found it difficultin many circumstances to process multidimensional oligomers that haveappreciable MW, so the properties of composites made frommultidimensional advanced composite blends might suffer because ofdiversity of MW. Furthermore, the addition polymerization reaction formultidimensional oligomers results in formation of a complex,3-dimensional network of crosslinked oligomers that is difficult orimpossible to match with the multidimensional polymers, because thesepolymers simply have extended chains or short chains. That is, uponcuring, the multidimensional oligomers crosslink to chemicallyinterconnect the arms or chains through the end caps, thereby forming anetwork of interconnected hubs with intermediate connecting chains. Theconnecting chains have moderate MW, although the oligomer can addappreciable MW upon curing. In contrast, the polymer (which does notcrosslink) simply has a hub with arms of moderate MW. While, for linearmorphology, the disadvantages of blended composites that have a widediversity of average MW polymers as constituents can be overcome bycuring relatively low MW oligomers into relatively high MW curedpolymers that are roughly equivalent to the polymer constituents, thepolymers in the multidimensional morphology are likely to have averageMW lower than the oligomeric component. Therefore, we believe we canachieve the best results for the present invention with systems havinglinear morphology where it is easier to achieve MW harmony in thecomposite.

Although we have yet to verify our theory experimentally, it may bepossible and desirable to synthesize the polymeric component of themultidimensional advanced composite blend when curing the oligomer, and,in that way, forming relatively comparable oligomeric and polymericnetworks. To achieve this effect, we would mix, for example, amultidimensional oligomer with comparable polymeric precursors, such astriamines and tricarboxylic acid halides. Upon curing, the precursorswould condense to form amide linkages to form bridges between hubs in amanner comparable to the oligomeric connecting chains.

The potential problem of structural mismatch and the proposed solutionfor achieving comparable MW in multidimensional advanced compositeblends likely also applies to coreactive oligomer blends to some degreeso that homopolymerization and addition polymerization compounds remaincomparable.

To overcome the problem of different MW between the oligomer and polymerin the composite, we theorize that it may be possible to prepare a blendthat includes the oligomer and polymeric precursors. For example, we canmix a polyether oligomer of the general formula: ##STR110## wherein ξ isthe residue of a four functional end cap monomer with polyamidepolymeric precursors of the general formula: ##STR111## so that, uponcuring, the oligomer crosslinks and the polymeric precursors condensethrough the amine and acid to form a polyamide polymer. This approachmay be best suited for the lower curing oligomers. The product mayinclude addition polymers and block copolymers of the oligomer and oneor both of the polymeric precursors. A Michaels addition might occurbetween the oligomer and amine multidimensional polymer, which would beundesirable.

The oligomers may be formed by the attachment of arms to the hubfollowed by chain extension and chain termination. For example,phloroglucinol may be mixed with p-aminophenol and4,4'-dibromodiphenylsulfone and reacted under an inert atmosphere at anelevated temperature to achieve an amino-terminated "star" of thegeneral formula: ##STR112## that can be reacted with suitable diacidhalides, dianhydrides, and end caps to yield an amide, amideimide,imide, or other oligomer. By substituting 2,4-diaminophenol foraminophenol, an ethersulfone compound of the formula: ##STR113## can beprepared When reacted with an acid halide end cap monomer to produce Zend groups the product is a multiple chemically functional ether sulfonemultidimensional oligomer. Extended amides, imides, etc. could also beprepared resulting in multidimensional oligomers with a high density ofcrosslinking functionalities.

As we have have discussed, the oligomers can be synthesized in ahomogeneous reaction scheme wherein all the reactants are mixed at onetime, or in a stepwise reaction scheme wherein (1) the radiating chainsare affixed to the hub and the product of the first reaction issubsequently reacted with the end cap groups or (2) extended end capcompounds are formed and condensed with the hub. Homogeneous reaction ispreferred, resulting undoubtedly in a mixture of oligomers because ofthe complexity of the reactions. The products of the processes (evenwithout distillation or isolation of individual species) are preferredoligomer mixtures which can be used without further separation to formthe desired advanced composites.

We can synthesize linear or multidimensional oligomers from a mixture offour or more reactants thereby forming extended chains. Addingcomponents to the reaction liquor, however, adds complexity to thereaction and to its control. Undesirable competitive reactions mayresult or complex mixtures of macromolecules having widely differentproperties may form, because the mixed chain extenders and chainterminators compete with one another.

The hub may also be a polyol such as those described in U.S. Pat. No.4,709,008. These polyols are made by reacting, for example,4-hydroxybenzaldehyde or 4-hydroxyacetophenone with an excess of phenolunder acid conditions (as disclosed in U.S. Pat. Nos. 4,709,008;3,579,542; and 4,394,469). The polyols may also be reacted withnitrophthalic anhydride, nitroaniline, nitrophenol, or nitrobenzoic acidto form other compounds suitable as hubs as will be understood by thoseof ordinary skill.

In synthesizing the polymers, we use quenching compounds to regulate thepolymerization (i.e., MW) of the comparable polymer, so that, especiallyfor linear systems, the polymer has a MW initially substantially greaterthan the crosslinkable oligomer. For thermal stability, we prefer anaromatic quenching compound, such as aniline, phenol, or benzoic acidchloride. We generally make the noncrosslinking polymer by the samesynthetic method as the oligomer with the substitution of a quenchingcap for the crosslinking end cap. Of course, we may adjust the relativeproportion of the reactants to maximize the MW.

While the best advanced composite blends are probably those where theindividual oligomers and polymers in the blend are of modest MW andthose in which the oligomer and polymer are initially in equimolarproportions, we can prepare other compositions, as will be recognized bythose of ordinary skill in the art. Solvent resistance of the curedcomposite may decrease markedly if the polymer is provided in largeexcess to the oligomer in the blend.

The advanced composite blends may include multiple oligomers or multiplepolymers, such as a mixture of an amideimide oligomer, an amideoligomer, and an imide polymer or a mixture of an amideimide oligomer,an amideimide polymer, and an imide polymer (i.e. blended amideimidefurther blended with imide). When we use polyimide oligomers, theadvanced composite blend can include a coreactant, such asp-phenylenediamine, benzidine, or 4,4'-methylenedianiline. Ethersulfoneoligomers can include these imide coreactants or anhydride oranhydride-derivative coreactants, as described in U.S. Pat. No.4,414,269. We can use other combinations of oligomers, polymers, andcoreactants, as will be recognized by those of ordinary skill in theart.

As discussed above, the oligomeric component of the advanced compositeblend may itself be a blend of the oligomer and a compatible polymerfrom the same chemical family, further blended with the compatiblepolymer from the different family. The advanced composite blendsgenerally include only one oligomeric component unless coreactiveoligomers are used.

Advanced composite blends are illustrated as follows.

EXAMPLE 48

Proposed linear amideimide/ether advanced composite blend

The polyamideimide oligomer of Example 10 is dissolved in a suitablesolvent. Make a relative high average formula weight polyether polymercondensing the diol:

    HO--.O slashed.--O--.O slashed.--O--.O slashed.--O--.O slashed.--OH

with Cl--.O slashed.--Cl and phenol (to quench the polymerization) underan inert atmosphere in the same solvent as used with the polyamideimideoligomer or another miscible solvent.

Mix the two solutions to form a lacquer of the advanced composite blend.Prepreg or dry the lacquer prior to curing to an advancedamideimide/ether composite.

EXAMPLE 49

Proposed multidimensional ether sulfone/ester advanced composite blend

Prepare a multidimensional, polyether sulfone polymer by reactingphloroglucinol with Cl--.O slashed.--Cl and HO--.O slashed.--O--.Oslashed.--SO₂ --.O slashed.--O--.O slashed.--OH, quenching thepolymerization with either .O slashed.--Cl or phenol to yield apolymeric product. The condensation occurs in a suitable solvent underan inert atmosphere. Do not recover the product from the solvent.

Prepare a multidimensional, polyester oligomer in the same solvent asused for the polymer or in another miscible solvent by condensingcyuranic acid chloride with a phenol end cap. Do not recover theproduct, but mix the oligomeric reaction mixture with the polymerproduct to form a varnish of a multidimensional advanced compositeblend. Prepregg or dry the varnish prior to curing to form amultidimensional, polyester/polyethersulfone, advanced composite.

15. Coreactive Oligomer Blends

Block copolymers are promising for tailoring the mechanical propertiesof composites while retaining ease of processing. The present inventionalso comprises blends of two or more coreactive oligomers analogous tothose blends described in U.S. Pat. No. 5,159,055. The oligomers areterminated with mutually interreacting caps that allow formation of theblock copolymer(s) upon curing. We can increase stiffness in this way inan otherwise flexible oligomer, although the four crosslinks themselvesincrease stiffness. For example, we can achieve stiffening for acomposite made from an ethersulfone oligomer by adding an imide oligomeras a coreactant. Those skilled in the art will recognize the benefits tobe gained through coreactive oligomer blends. Generally, at least one ofthe oligomers in the coreactive oligomer blend will include fourcrosslinking functionalities at each end of the backbone.

We generally prepare block copolymers formed from the coreactiveoligomer blends by blending an oligomer of the general formula:

    ξ--R.sub.4 --ξ

wherein

R₄ =a divalent hydrocarbon radical, as we have described; and

ξ=a four functional hydrocarbon residue of an end cap monomer used toform the oligomer

with a coreactive oligomer of the general formula:

    Z*.sub.k --B--Z*.sub.k

wherein

k=1, 2, or 4;

B=a hydrocarbon backbone that is from the same or a different chemicalfamily as R₄ ;

Z*=a hydrocarbon residue including a segment selected from the groupconsisting of: ##STR114## ρ=--O-- or --S--; and --.O slashed.--=isphenylene.

Preferably we select the oligomeric backbones from the group consistingof imidesulfones, ethersulfones, carbonates, esteramides, amides,ethers, esters, estersulfones, imides, etherimides, amideimides, cyanateesters, and, more preferably, the ethers, esters, sulfones, or imides.Generally, the hydrocarbons are entirely aromatic with phenyleneradicals between the linkages that characterize the backbones. Theoligomers can be linear or multidimensional in their morphology. Thecomponents of these coreactive blends should have overlapping melt andcuring ranges so that the crosslinking functionalities are activated atsubstantially the same time, so that flow of the blend occurssimultaneously, and so that, for heterocycles, the chain-extensionoccurs in the melt where the products are soluble. Matching the melt andcuring ranges requires a selection of the chemistries for the coreactiveblend components, but achieving the match is readily within the skill ofthe ordinary artisan.

The coreactive oligomer blends can comprise essentially any ratio of thecoreactive oligomers. Changing the ratio of ingredients, of course,changes the physical properties in the final composites. Curing thecoreactive oligomers involves mutual (interlinking) polymerization andaddition polymerization. Therefore, we generally use equimolar mixturesof the ingredients (i.e., the ξ and Z* components) in the blends.

The individual oligomers should initially have relatively low MW(preferably no more than and, generally, around 10,000) and,accordingly, should remain relatively easy to process until the curingreaction when extended chain and block copolymers form to produce thecomposite. A complex mixture of at least three types of addition polymerform upon curing.

The coreactive oligomer blends can also include noncrosslinkingpolymers, as desired, to provide the desired properties in thecomposites. That is, the coreactive blend may include the twocrosslinking oligomers and a noncrosslinking compatible polymer, therebyforming a blend with three or more resin components.

We can prepare oligomers of the general formula ξ--R₄ --ξ or Z*_(k)--B--Z*_(k) by reacting suitable end cap monomers with the monomerreactants that are commonly used to form the desired backbones. Forexample, we prepare an imidesulfone as we have already described byreacting a sulfone diamine with a dianhydride. We prepare ethersulfonesby reacting a suitable dialcohol (i.e. diol, bisphenol, or dihydricphenol) with a dihalogen as described in U.S. Pat. No. 4,414,269.Similarly, the end cap monomers for the Z*_(k) --B--Z*_(k) oligomersgenerally are selected from the group consisting of aminophenol,aminobenzoic acid halide, H₂ N--.O slashed.--SH, .O slashed.--W, or thelike, wherein W--OH, --NH₂, or --COX. The Z*_(k) --B--Z*_(k) oligomersinclude any diamines, diols, or disulfhydryls we have previouslydescribed. In this circumstance, k=1.

Upon curing, the oligomers homopolymerize (i.e. addition polymerize) bycrosslinking and form block copolymers through the Michaels additionreaction between the hydrocarbon unsaturation of one oligomer and theamine, hydroxyl, or sulfhydryl group of the other. The reaction of thehydrocarbon unsaturation of one oligomer with the functionality of theother follows the mechanism described in U.S. Pat. No. 4,719,283 to forma cyclohexane linkage by bridging across the double bond. With theacetylene (triple) unsaturation, a cyclohexene ring results.

The Michaels addition reaction is illustrated as follows: ##STR115##wherein V=--NH--, --O--, or --S--. For the other end caps, we believe areverse Diels-Alder decomposition reaction (induced by heating theoligomers) results in the formation of a reactive maleic moiety and theoff-gassing of a cyclopentadiene. The methylene bridge decomposes to themaleic compound at about 625°-670° F. (330°-355° C.) while the --O--bridge decomposes at the lower temperature of about 450° F. (230° C.).

The reactive group might also be --CNO instead of the amine, but we donot recommend use of these dicyanates.

While we have described preferred embodiments, those skilled in the artwill readily recognize alterations, variations, and modifications whichmight be made without departing from the inventive concept. Therefore,interpret the claims liberally with the support of the full range ofequivalents known to those of ordinary skill based upon thisdescription. The examples are given to illustrate the invention and notintended to limit it. Accordingly, limit the claims only as necessary inview of the pertinent prior art.

We claim:
 1. An advanced composite blend comprising a mixture of atleast one compatible polymer from a chemical family different from anoligomer with which the polymer is mixed and the oligomer, the oligomerbeing made by the process of(a) condensing diaminophenol directly with alinear or multidimensional intermediate selected from:

    α--(--R.sub.4 --)--α

or

    ∂-- --(R.sub.# --)--α!.sub.w

wherein R₄ is a divalent organic aromatic radical; R_(#) is R₄ or bond;∂ is a organic aromatic hub radical of valency "w"; w is 3 or 4; and αis an organic functionality reactive with --OHor indirectly with amixture of reactive monomers that condense to yield

    α--(--R.sub.4 --)--α

or

    ∂-- --(R.sub.# --)--α!.sub.w

the condensation yielding a four functional, bis, amine of the formula:

    (H.sub.2 N--).sub.2 --(R.sub.? --)--(NH.sub.2).sub.2 or

    ∂-- --(R.sub.# --)----.O slashed.--(--NH.sub.2).sub.2 !w

wherein R_(?) is a residue resulting from the condensation of step (a);.O slashed. is phenylene; and is a moiety resulting from the α--/--OHcondensation; and (b) condensing the four functional, bis, amine of step(a) with an acid halide of the formula: ##STR116## to yield an oligomerof the formula: ##STR117## wherein δ is phenylene or pyrimidinylene; iis 1 or 2; E is ##STR118## G is --CH₂ --, --C(HR₃)--, --C(R₃)₂ --,--S--, --SO₂ --, --O--, or --CO--; R₃ is lower alkyl, lower alkoxy,aryl, aryloxy or hydrogen and; Θ is --C.tbd.N, --O--C.tbd.N,--S--C.tbd.N, or --CR₃ ═C(R₃)₂ ; T is allyl or methallyl; and Me ismethyl;provided that Θ is not --CN, --OCN, or --SCN, when β is --OCN, orthe oligomer is made by the process of: condensing a multiple chemicallyfunction acid halide of the formula: ##STR119## directly with a linearor multidimensional intermediate reactive with the --COX or indirectlywith a mixture of monomers that condense to yield an intermediatereactive with the --COX, wherein X is halogen.
 2. An advanced compositeblend made by(a) preparing a multiple chemically functional oligomer byreacting a crosslinking end cap monomer of the formula:

    (Z--).sub.i --δ--β

with a monomer reactive with the β of the end cap monomer, wherein: δ isphenylene or pyrimidinylene; Z is ##STR120## β is an organic radicalselected from the group consisting of: ##STR121## X is halogen; R₈ andR*₈ is a divalent organic aromatic radical; E is ##STR122## G is --CH₂--, --C(HR₃)--, --C(R₃)₂ --, --S--, --SO₂ --, --O--, or --CO--; T isallyl or methallyl; and Me is methyl; R₃ is lower alkyl, lower alkoxy,aryl, aryloxy, or hydrogen and; Θ is --C.tbd.N, --O--C.tbd.N,--S--C.tbd.N, or --CR₃ ═C(R₃)₂ ;provided that Θ is not --CN, --OCN, or--SCN, when β is --OCN, and (b) blending the oligomer with a polymer toform the blend.
 3. The blend of claim 1 wherein i is 2 so that there arefour unsaturated hydrocarbon moieties available for crosslinking.
 4. Theblend of claim 1 wherein the oligomer is selected from the groupconsisting of imidesulfone, ether, ethersulfone, amide, imide, ester,estersulfone, esteramide, etherimide, amideimide, cyanate ester, andcarbonate.
 5. The blend of claim 4 wherein the oligomer and polymer areselected from the following table of oligomer/polymer pairs:

    ______________________________________                                        OLIGOMER           POLYMER                                                    ______________________________________                                        amideimide         imide                                                      imide              amideimide                                                 amideimide         heterocycle                                                amideimide         heterocycle sulfone                                        imide              heterocycle                                                imide              heterocycle sulfone                                        imide              amide                                                      amide              imide                                                      ester              amide                                                      amide              ester                                                      estersulfone       amide                                                      ester              esteramide                                                 amide              estersulfone                                               ester              imide                                                      imide              ester                                                      estersulfone       imide                                                      ______________________________________                                    


6. The blend of claim 1 further comprising a second oligomer of thegeneral formula:

    Z*.sub.k --B--Z*.sub.k ;

wherein k is 1, 2, or 4; B is an aromatic, aliphatic, or mixed aromaticand aliphatic backbone; Z* is a hydrocarbon residue including a segmentselected from the group consisting of: ##STR123## E is selected from thegroup consisting of: ##STR124## Θ is --C.tbd.N, --O--C.tbd.N,--S--C.tbd.N, or --CR₃ ═C(R₃)₂ ; G is --CH₂ --, --C(HR₃)--, --C(R₃)₂ --,--S--, --SO₂ --, --O--, or --CO--; T is methallyl or allyl; Me is methyli is 1 or 2; and R₃ is hydrogen, lower alkyl, lower alkoxy, aryl, oraryloxy.